[Plugin: Featured Posts Grid] Using FPG with another Plugin

Hello.
I’d like to have FPG use the authors photo which is uploaded by the user-photo plugin. I modified the section of code line 416 in featured-posts-grid.php to call the userphoto function.: $post_details[$key][‘post_img_src’][0] = userphoto_the_author_thumbnail();

However, the photo show up above the actual thumbnail. Using firebug shows that the src=”.
Apparently the function retrieves the photo but isn’t able to insert where I want? Here’s the page:
https://www.coachsomebody.com/library/