Not sure if you have figured it out yet, but I think the problem is where you register your startup script. It should point to the page (page where the control is loaded) and not to the control itself. You can try : ScriptManager.RegisterStartupScript(this.Page,typeof(this.Page.getType()) ,"ScriptKey","alert('HI')", true); Hope this helps.

this the same problem to me any solve????

it is in ajax toolkit. i want to just make like orkut scrap replay editor so i can add image in add control. i hv done all except that image display. hv u any idea abt this if yes then plz suggest me. thank's

Hi, Try this tag on page. <pages validateRequest="false" enableEventValidation="false" /> but it is not recommended because it is security feature so that disabling it should be considered carefully. Regards, Jamil