unable to Pop-up messages

Dear All;
             I have made a customize page and  write the following code in People Tools 8.5

WinMessage("HELLO U ALL", 0, "MessageE");    on pushbutton fieldedit



If %Language = "ARA" Then
   MessageBox(0, " ", 21000, 1, "ARABIC");
Else
   MessageBox(0, " ", 21000, 1, "ENGLISH");
End-If;                                                                         on pushbutton field change  (21000,1 defined in message catalog)

But pop-up message doesn't comes, I tested it on IE 9.0 as well as Mozilla Fire Fox 3.6, I also turn off pop-up blocked and also enable Java script and I am using Windows Vista 32 Bit


So please can any one tell me, where is the problem

Thanks
Kamran Chagani