Attachment Extender Errors

Hello,

I just updated my theme and when I went to edit a post, I noticed that my attachment extender plugin (used for inserting multiple images at once into post) was no longer working and would return this error into the post instead of the images:

Fatal error: Call to undefined function get_image_send_to_editor() in /home/cpa/public_html/wp-content/plugins/attachment-extender/attachment-extender.php on line 23

Anybody know what might be causing this?

Thanks