javascript issue in jsf/icefaces

jsf comm开发者_JAVA技巧and button doesn't invoking javascript , please suggestions

<ice:commandButton id="submit" onclick="validationmessage();" value="Submit"

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1. Check page source. Does validationmessage() function exist in it?
2. Check if onclick works. Put something like "alert('blabla')" there. Does it work?