Show Userform if cell with specific text is pressed

Hello all,

I was wondering if it would be possible to display a Userform if a cell with specific text is pressed. I've gotten this to work with the following code, but if multiple cells are selected, an error appears.

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If Target.Value = "This Text" Then
    UserformX.Show
Else
    Exit Sub
End If

End Sub