wildcard with GUICTRLREAD label

I search a couple post, but those method are only for searching for files.

What I'm doing here is a little different. I want the button to prompt a message "This is a server PC!" if the label contain starting Text "CT".

Label will randomly change because Label is getting hostname by TCPIPTONAME.

This is what I got so far, but not working as expected:

If StringInStr($Label, "CT", 0, 1) Then
    MsgBox(0, "Test", "This is a Server PC, you cannot change its name!")
Else
    MsgBox(0,"", "End!")
EndIf