Changing FCKEditor value from another window

I used the following code to add HTML to fckeditor from a window popup that opened on the page with fckeditor...

opener.frames[0].objContent.DOM.body.innerHTML += variable;

the frames[0] thingy changes if you have multiple fckeditors on one page, 0 being the first, 1 being the second etc..

Hope that helps

I succeeded with the following code:

function DoInsertImage( myValue ) {
window.opener.frames[0].objContent.DOM.selection.clear() ;
window.opener.frames[0].objContent.DOM.selection.createRange().pasteHTML(myValue) ;
}

I've tried the ex above but don't work:
"'parent.frameheader.txtCorpoMens.DOM.body' is null or not an object".

txtCorpoMens is the parameter int the constructor:

oFCKeditor = new FCKeditor('txtCorpoMens');

Could you post the exact code that did result in that error message?