Hi, You can not deselect item from list you have to select atleast one item.For your purpose you can add one empty('') value as item in list,which can be set if don't want anty item to select. regards, Nagraj

that i know but i just want to ignore the exception because rest functnality is working fine.

Hi! There is a website that contains free online tutorials. I used the search criteria: "web part" and I found a tutorial that walks through a process that might be the answer of your question. Why don't you go ahead and try it: http://www.KYNOU.com