Custom web part with people editor not setting __EVENTTARGET on postback

Question

I have a people editor that is set to autopostback. The postback is triggered fine and I need to check that the people editor is the responsible control.

Suggestions that I've found direct to checking the request form. Like:

string ctrlname = page.Request.Params.Get("__EVENTTARGET");

But ctrlname is returning null. How can I confirm that the people editor is triggering the call back?

Thanks.