Value cannot be null. Parameter name: ms_no

Dear Coders,

I did a simple program to fill data by by the event ComboBox_SelectedIndexChanged in the code below. A Null error is happening unexpectedly. What will be the problem and Please Suggest me a solution. The Full code is below. And i also have a parameter called ms_no.

Public Class Form1

    Private Sub E1BindingNavigatorSaveItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles E1BindingNavigatorSaveItem.Click
        Me.Validate()
        Me.E1BindingSource.EndEdit()
        Me.TableAdapterManager.UpdateAll(Me.ProcurementDataSet)

    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        'TODO: This line of code loads data into the 'ProcurementDataSet.Project' table. You can move, or remove it, as needed.
        Me.ProjectTableAdapter.Fill(Me.ProcurementDataSet.Project)
        'TODO: This line of code loads data into the 'ProcurementDataSet.E1' table. You can move, or remove it, as needed.
        Me.E1TableAdapter.Fill(Me.ProcurementDataSet.E1)

    End Sub

    Private Sub ComboBox2_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox2.SelectedIndexChanged
        Me.E1TableAdapter.FillBy(Me.ProcurementDataSet.E1, ms_no:=ComboBox2.SelectedValue)

    End Sub
End Class

Tags: Visual Basic, Visual Studio 2010