ติด error Input string was not in a correct format. รบกวนหน่อยคะ

Imports System.Data
Imports System.Data.SqlClient
Public Class MResou
    Inherits System.Web.UI.Page

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        If Not IsPostBack Then
            TxtResou.Text = ""
            TxtQty.Text = ""            
            TxtResou.Focus()
        End If
        BRDel.Attributes.Add("onclick", "if(!window.confirm('Are you sure delete record??'))" & "return false;")
        If Not IsPostBack Then
            BindData()
        End If
    End Sub

    Protected Sub BREdit_Click(ByVal sender As Object, ByVal e As EventArgs) Handles BREdit.Click
        If lstResou.SelectedIndex < 0 Then
            lblMessageR.Text = "Please Select Resource"
            Return
        End If
        Dim strConn As String = "Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Rescuedb.mdf;Integrated Security=True;User Instance=True"
        Dim objConn As New SqlConnection(strConn)
        objConn.Open()
        Dim cmdSQL As String = "SELECT ResouID,Resou,Qty " & " FROM dbo.Resource WHERE ResouID =" & lstResou.SelectedItem.Value
        Dim Cmd As New SqlCommand(cmdSQL, objConn)
        Dim RR As SqlDataReader
        RR = Cmd.ExecuteReader(System.Data.CommandBehavior.CloseConnection)
        While RR.Read()
            lblResouID.Text = RR("ResouID")
            TxtResou.Text = RR("Resou")
            TxtQty.Text = RR("Qty")
        End While
        TxtResou.Enabled = True
        TxtQty.Enabled = True
        BRUpdate.Visible = True
        BRDel.Visible = True
        lblMessageR.Text = ""
        lblErrorResou.Visible = False
        lblErrorQty.Visible = False
    End Sub

    Protected Sub BRDel_Click(ByVal sender As Object, ByVal e As EventArgs) Handles BRDel.Click
        'Delete Data
        Dim strConn As String = "Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Rescuedb.mdf;Integrated Security=True;User Instance=True"
        Dim objConn As New SqlConnection(strConn)
        objConn.Open()
        Dim cmdSQL As String = "DELETE FROM dbo.Resource " & " WHERE ResouID=@ResouID"
        Dim Cmd As New SqlCommand(cmdSQL, objConn)
        Cmd.Parameters.Add("@ResouID", SqlDbType.Int).Value = Me.lblResouID.Text
        Cmd.ExecuteNonQuery()
        objConn.Close()
        BindData()
        lstResou.Focus()
        lblMessageR.Text = "Successfully Delete:" & TxtResou.Text & " " & TxtQty.Text
        TxtResou.Enabled = False
        TxtQty.Enabled = False
        BRUpdate.Visible = False
        BRDel.Visible = False
    End Sub

    Protected Sub BRAdd_Click(ByVal sender As Object, ByVal e As EventArgs) Handles BRAdd.Click
        lblErrorResou.Visible = False
        lblErrorQty.Visible = False
        'Check Error input
        If TxtResou.Text = "" Then
            lblErrorResou.Visible = True
            lblErrorR.Text = "Please Enter Name"
            TxtResou.Focus()
            Return
        End If
        If TxtQty.Text = "" Then
            lblErrorQty.Visible = True
            lblErrorR.Text = "Please Enter age"
            TxtQty.Focus()
            Return
        End If
        
        'Insert Data into SQL Server 2008
        Dim strConn As String = "Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Rescuedb.mdf;Integrated Security=True;User Instance=True"
        Dim objConn As New SqlConnection(strConn)
        objConn.Open()
        Dim cmdSQL As String = "INSERT INTO dbo.Resource" & "(Resou,Qty)" & "VALUES(@Resou,@Qty)"
        Dim Cmd As New SqlCommand(cmdSQL, objConn)
        Cmd.Parameters.Add("@Resou", SqlDbType.NVarChar).Value = Me.TxtResou.Text
        Cmd.Parameters.Add("@Qty", SqlDbType.Char).Value = Me.TxtQty.Text
        Cmd.ExecuteNonQuery()
        objConn.Close()
        lblErrorR.Text = "Successfully Insert:" & TxtResou.Text & " " & TxtQty.Text
        TxtResou.Text = ""
        TxtQty.Text = ""
        TxtResou.Focus()
    End Sub

    Protected Sub BRUpdate_Click(ByVal sender As Object, ByVal e As EventArgs) Handles BRUpdate.Click
        'Check Error input
        lblMessageR.Text = ""
        lblErrorResou.Visible = False
        lblErrorQty.Visible = False
         If TxtResou.Text = "" Then
            lblErrorResou.Visible = True
            lblErrorR.Text = "Please Enter Name"
            TxtResou.Focus()
            Return
        End If
        If TxtQty.Text = "" Then
            lblErrorQty.Visible = True
            lblErrorR.Text = "Please Enter age"
            TxtQty.Focus()
            Return
        End If

        'Update Data
        Dim strConn As String = "Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Rescuedb.mdf;Integrated Security=True;User Instance=True"
        Dim objConn As New SqlConnection(strConn)
        objConn.Open()
        Dim cmdSQL As String = "UPDATE dbo.Resource " & " SET Resou=@Resou,Qty=@Qty " & " WHERE ResouID=@ResouID"
        Dim Cmd As New SqlCommand(cmdSQL, objConn)
        Cmd.Parameters.Add("@ResouID", SqlDbType.Int).Value = Me.lblResouID.Text
        Cmd.Parameters.Add("@Resou", SqlDbType.NVarChar).Value = Me.TxtResou.Text
        Cmd.Parameters.Add("@Qty", SqlDbType.Char).Value = Me.TxtQty.Text
        Cmd.ExecuteNonQuery()
        objConn.Close()
        BindData()
        lstResou.SelectedIndex = lstResou.Items.IndexOf(lstResou.Items.FindByValue(lblResouID.Text))
        lstResou.Focus()
        lblMessageR.Text = "Successfully Update:" & TxtResou.Text & " " & TxtQty.Text
        TxtResou.Enabled = False
        TxtQty.Enabled = False
        BRUpdate.Visible = False
        BRDel.Visible = False
    End Sub

    


    Sub BindData()
        Dim strConn As String = "Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Rescuedb.mdf;Integrated Security=True;User Instance=True"
        Dim objConn As New SqlConnection(strConn)
        objConn.Open()
        Dim cmdSQL As String = " SELECT ResouID," & " Resou+''+Qty As ResourceData " & " FROM dbo.Resource "
        Dim Cmd As New SqlCommand(cmdSQL, objConn)
        Dim RR As SqlDataReader
        RR = Cmd.ExecuteReader(System.Data.CommandBehavior.CloseConnection)
        lstResou.DataSource = RR
        lstResou.DataValueField = "ResouID"
        lstResou.DataTextField = "ResourceData"
        lstResou.DataBind()
        If lstResou.Rows > 0 Then
            lstResou.SelectedIndex = 0
        End If
        lstResou.Focus()
        objConn.Close()
    End Sub
End Class