Appending Text to vb Editor Textarea

[Aytrydez]

I need a way to have a Javascript function append text to the vbulletin editors textarea when posting a new thread/post. I have written a custom image upload script for my forum that is used during new posts, it allows a member to select an image, upload it to the server and then provides a reference to the image in the form of a link, what I have tried to do is write a javascript function that will take the link and format a string with bb IMG tags, and then append the string to the VB Editor textarea, however when i reference the textarea by id in javascript, using getElementsById('VB_Editor_001_textarea') and subsequently try to append a string to the value property of the element, i receive this error in firefox:

Error: [Exception... "Component returned failure code: 0x80004003 (NS_ERROR_INVALID_POINTER) [nsIDOMNSHTMLDocument.queryCommandState]"  nsresult: "0x80004003 (NS_ERROR_INVALID_POINTER)"  location: "JS frame :: http://orlounge.com/forum/clientscript/vbulletin_textedit.js?v=364 :: anonymous :: line 1415"  data: no]
Source File: http://orlounge.com/forum/clientscript/vbulletin_textedit.js?v=364
Line: 1415

any help would be appreciated.