Viewing Attachment Photo on Form

I have a check-out type database where once an item is checked out,
the "Check Out" form pops up. Everything works except that I want the
photo of the person that is checking the item out. The check out form
is based on a transaction tble. The table does not have the
"attachments" field. The photo attachment is stored in my contact
tbl. I have tried several things, such as queries (Transaction Tbl,
Contact Tbl) but error " The current field must match the join Key "?"
etc. I know there is an easy fix, currently I don't have it. I just
want to use it as a visual security reference when checking out the
item.

Any help would be greatly appreciated.