Please make sure you have download the correct vbgallery for your vbulletin version and uploaded all files to the proper places from the downloaded code.
Your vbulletin forum is functional? to my knowledge that function is a vbulletin function.
Yes vbulletin version 3.7.2 is functional and have correct gallery version 2.51
have followed all install instructions.
but install hangs with that error