FormAPI - Setting Container value using callserver

System

Hi,

I have a container which contain 5 items. OnITemChange event of Item 1 , I am calling perl script using callserver.

no I want to set some value in 2nd Item of same container but i unable to do this ..

[PHP]
function populateFileSize(filesize)
{
//working
IWDatacapture.getItem("/graphics/graphic[1]/caption").setValue(filesize);
// not working
IWDatacapture.getItem("/graphics/graphic/caption").setValue(filesize);

}


[/PHP]


Problem : how do i know which container has sent a request so that i set the value in same container ...

Can we calculate container no using form API so that i can pass it as paramater and set it back ?


Thanks
Vinay