Why can't i open jpg files on my phone?

[Android Central Question]

So I am downloading jpg photos as attachments from a facilities management app called espace, but when I try to open them via the download notification or through the file manager I get the error "can't open file." I know the files have downloaded successfully because 1) the file manager displays a thumbnail preview of the photo, and 2) manually opening adobe Photoshop express from my app drawer allows me to open the file through the app directly. I considered trying to set Photoshop as the default app for jpg files, but I can't figure out how, because tapping the file in the file manager never gives me an option to select which app to use. Please help.

 

[ManiacJoe]

Which phone?
Which version of android?
Which carrier?
Which file browser app?
Which folder are the files saved to?