pasteHTML in dialogbox.html givind unspecified error

Hi all

i have created a plugin. In that i am using the below code . when the code reaches the line pasteHTML, it raise a error like "unspecified error". I dont know why this error is coming. What should i do to resolve this error. Please help me regarding this...

And I have tested the code with a button's onclick event which resides in the main document not in the dialog window document. It is pasted the specified image into the editor...

var oEditor = FCKeditorAPI.GetInstance('FCKEditor1');
var range = oEditor.EditorDocument.selection.createRange();
range.pasteHTML("<img src='http://innovation-dev.unilever.com/inoplan2/cat_tw/tw8215013.nsf/0/A51F43E8A52EDA65C12572D8007684E3/$FILE/find.gif'></img>");

Thanks in advance.....
Rams K