show syntax error while executing while loop

Hi i found syntax error when implementing while loop to wait for object of my desktop application.

def test13():
Sys.WaitProperty("btnYes", 200)
Aliases.CTCUI.dlgWarning.btnYes.ClickButton()
var i = 1;
while (i < 3) {
NameMapping.Sys.CTCUI.dlgInformation.btnOK.Click();
i++;
}