I am knew to the gadget api,i've been trying to set user preferences for a while,but had no success so far,i have managed to get user preferences though.

Here the code i used which sort of hangs up the gadget

user_prefs.set("ltxt",str);

---------------------------------------------------------- user_prefs is the preferences object,ltxt is a string type preference and str js string variable,

if remove the above line the gadget works fine,but how do i get the set preference thing working?what am i doing wrong?