VBNET2008 -runtime Error message

[Lennie]

Hi Good Guys and Helpers

I have received an error message which I could not figure it out.

Error message
No mapping exists from object type System.Windows.Forms.TextBox to a known Manage provider native type
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The code below generates this error message at runtime.

 Private Sub FUpdateExistingRecord()
   
         
 try
        Dim strSql As String = Nothing
        strSql = "Update TestCustomers"
        strSql &= " Set CompanyName = @custName "  
        strSql &= " Where CustomerId = @CustID"

        sqlconn = New SqlConnection(connstr)
        sqlconn.Open()
        sqlCmd = New SqlCommand(strSql, sqlconn)

        With sqlCmd.Parameters
            .AddWithValue("@CustId", Me.txtCustID.Text)
            .AddWithValue("@CustName", Me.txtCompanyName.Text)
       End With

       sqlCmd.ExecuteNonQuery
      sqlconn.close

Catch Ex as Exception
	messagebox.show(ex.message)
End Try