Hi @Aurora
I tried this from my side, its working perfectly fine for me.
This may help for you.
1) Add on Textbox, in OnClear add this code :
If (Value(Inputbox.Text) <= 0 and Value(InputBox.Text) > 12, true, false)
2) Add on label below and show popup when they enter less than 0 and more than 12.
If (Value(Inputbox.Text) <= 0 and Value(InputBox.Text) > 12, true, false) add this code on label onvisible.
If this solve your issue please mark as solved.