I have a gridview that has a ButtonField(Ins ert) that calls a detailsview which allows you to insert data to the gridview. The postback for this buttonField is:
"javascript:__d oPostBack('ctl0 0$POPAContentPl aceHolder$grdRe marks','Insert$ 0')", which takes me to the details view and were I click on a 'New' link with it's postback:

"javascript:__d oPostBack('ctl0 0$POPAContentPl aceHolder$grdRe marks$ctl01$Det ailsView2','New $0')"...