Call User form only if cell value is ""

Hi Guys,
I'm trying to call a user form from a range of cells only if cell value F3 is equal to "Shift B" I have the following in:

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If Not Intersect(Target, Range("N20:N47")) Is Nothing And Range("F3") = ("ShiftB") Then PickTechB.Show
End Sub

I have tried several combinations but am unable to find a solution, any help would be gratefully received.
Regards
Spagbog