Thick box (thickbox) Automatic pop-up error

A project uses the pop-up Div window,
In addition, you can set the window that will pop up after one day. However, we found that the window is grayed out, but the progress bar and window of which is loaded are not displayed. (IE6 and IE7 are faulty. Firefox is fine)

An error occurred on line 51.
$ ("Body "). append ("<Div id = 'tb _ load'> </div>"); // Add loader to the page
During loading, imgloader may not be initialized successfully. The called function goes first.
Temporary solution
Replace imgloader. SRC with tb_pathtoimage.
CodeAs follows:
$ ("Body "). append ("<Div id = 'tb _ load'> </div>"); // Add loader to the page