Checking for Null

[venerable bede]

The following code :

If Not objROw2(0).Item("ClientLocality") Is Nothing Then
Me.lblLocality.Text = objROw2(0).Item("ClientLocality")
End If

Causes the following error when it contains nothing:

Additional information: Cast from type 'DBNull' to type 'String' is not valid.

Whats happening??

Thanks in Advance