grouping listview case-insensitive

Hi All.

I grouping ListView by that way

Dim DeptListSource = CType(Me.Resources("cvEmpDeptList"), CollectionViewSource)
Dim groupDescription As PropertyGroupDescription = New PropertyGroupDescription("Department")
DeptListSource.GroupDescriptions.Add(groupDescription)

It is grouping but it considers "Accounting" and "accounting" to be different groups. Is there a way to grouping it should go for case in-sensitive way? If is possible, how to modify grouping code?

Thanks.