embed photo album hosted on flickr.com using flickr module not showing photo album
It's likely you have photos in that set that aren't available in the size you've set the photos to display in. 

Flickr module documentation > Sizes


  TAKE CARE, the c (800px) size is missing on Flickr images uploaded before March 1, 2012. Check if it exists on the Flickr photo page > Actions > View all sizes.


More info and debug inspiration in the 7.x documentation: Flickr Editor Guide 7.x-1.7