exception occured on query when i Edit or Delete row from wpf datagrid using LINQ to SQL in c#

Hi and Assalam o Alaikum,

I am new to wpf c#.

I am trying CRUD operations on WPF Datagrid. My datagrid shown records from two table that are linked with foreign key reference.

here is backend code.

privatevoidLoadDataGrid(){DataClassesDataContext dataContext =newDataClassesDataContext();var results =from b in dataContext.iBankNames
                      join acc in dataContext.iBankAccountNos on b.BankID equals acc.BankIdorderby b.Name ascendingselectnew{BankID= b.BankID,BankName= b.Name,BankAccNo= acc.BankAccNo,BranchName= acc.Branch};MyDataGrid.ItemsSource= results;}

But the problem is occured when i edit a cell data and click on submit button the following message shown by exception.

ERROR:"Excetpion has thrown by the target on invocation" and it point me on linq to sql query that i have written in edit code.

Same problem is occured when i perform Delete operation.

here is my XML Code of wpf.

<DataGridx:Name="MyDataGrid"x:Uid="MyDataGrid"AutoGenerateColumns="False"SelectionMode="Single"AlternationCount="2"><DataGrid.Columns><DataGridTemplateColumnHeader="Bank ID"Width="SizeToHeader"><DataGridTemplateColumn.CellTemplate><DataTemplate><TextBoxIsReadOnly="True"Text="{Binding BankID,Mode=OneWay}"/></DataTemplate></DataGridTemplateColumn.CellTemplate></DataGridTemplateColumn><!----HERE ARE SOME MORE COLOUMNS-----><DataGridTemplateColumnHeader="Edit Row"><DataGridTemplateColumn.CellTemplate><DataTemplate><ButtonContent="Edit"Click="EditButton_Click"/></DataTemplate></DataGridTemplateColumn.CellTemplate></DataGridTemplateColumn><DataGridTemplateColumnHeader="Delete Row"><DataGridTemplateColumn.CellTemplate><DataTemplate><ButtonContent="Delete"Click="DeleteButton_Click"/></DataTemplate></DataGridTemplateColumn.CellTemplate></DataGridTemplateColumn></DataGrid.Columns></DataGrid>

Here is Edit code:

privatevoidEditButton_Click(object sender,RoutedEventArgs e){try{DataClassesDataContext dataContextEdit =newDataClassesDataContext();
            iBankName bankRow =MyDataGrid.SelectedItemas iBankName;//string m = customerRow.CustomerID;
            iBankName bank =(from p in dataContextEdit.iBankNameswhere p.BankID== bankRow.BankIDselect p).Single();

            bank.Name= bankRow.Name;

            iBankAccountNo banAccRow =MyDataGrid.SelectedItemas iBankAccountNo;

            iBankAccountNo bankAccNo =(from p in dataContextEdit.iBankAccountNoswhere p.BankAccNo== banAccRow.BankAccNoselect p).Single();

            bankAccNo.BankAccNo= banAccRow.BankAccNo;
            bankAccNo.Branch= banAccRow.Branch;

            dataContextEdit.SubmitChanges();MessageBox.Show("Row Updated Successfully.");}catch(ExceptionEx){MessageBox.Show(Ex.Message);// return;}}