Setting validationGroup on postback in asp.net 3.5 -

i have several server controls textbox, dropdowns in asp.net page. have requredfieldvalidators above fields errormessage="required".

i have button called btnsave.

for requiredfieldvalidators, have validationgroup="save" , have same btnsave.

now 1 of dropdowns, ddlresult if value 299 don't want requirefieldvalidator work.

in code behind selectedindexchange of ddlresult have this

protected void ddresult_selectedindexchanged(object sender, eventargs e)         {             if (ddresult.selectedvalue != "399")             {                 rfv1.validationgroup = "save";             }             else             {                 rfv1.validationgroup = "";             }         } 

inspite of doing requiredfieldvalidator getting fired. requiredfieldvalidator.

any thoughts??

set causevalidation property of dropdownlist false.