Dataview problems [resolved]

[Oliver1]

Okay, I have two combo boxes on a form, both displaying a different column from the same datatable, I want both these combo boxes to be sorted alphabetically though, so I created a dataview as so

ds.Tables.Add("ContactsCom")
ddiView = New DataView(ds.Tables("ContactsCom"))

I then bind the combo boxes as follows

Me.cbocompany.DataSource = ds
        Me.cbocompany.DisplayMember = "ContactsCom.CompanyName"
        Me.cbocompany.ValueMember = "ContactsCom.ContactID"
 
        ddiView.Sort = "MID"
 
        cboddi.DataSource = ddiView
        Me.cboddi.DisplayMember = "MID"
        Me.cbocompany.ValueMember = "ContactID"

Which all seems to work fine, but my problem now is that on the
cbocompany combo box this works

Private Sub cbocompany_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cbocompany.SelectedIndexChanged
 
        Try
 
            MsgBox(cbocompany.SelectedValue)
        Catch ex As Exception
            MsgBox(ex.ToString)
        End Try
 
    End Sub

But on the cboddi box I get the exception

Private Sub cboddi_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboddi.SelectedIndexChanged
        
        Try
            MsgBox(cboddi.SelectedValue)
       
        Catch ex As Exception
            Me.TextBox1.Text = ex.ToString
        End Try
 
    End Sub

System.ArgumentException: Argument 'Prompt' cannot be converted to type 'String'.

Why?