Your IF statements need to define their upper limits just under the
threshold of the next limit...otherwise they will all trigger....is
that what you wanted?
Example:
If size >= 10 And size < 20 Then
Label7.Visible = True
Else
Label7.Visible = False
End If
If size >= 20 And size < 30 Then
Label8.Visible = True
Else
Label8.Visible = False
End If
