Why can I not print attachments from gmail on my ipad mini, it will print photos and anything from safari

What are the attachments?

Do you have an App which can handle them? If so, open the attachment with that App and print.

Do you have an Airprint-capable printer or are using an App to print?

Some more details please.

For Gmail attachments, if they are PDF files (as well as many other formats) when you are viewing them on the iPad in Safari there is an option to "Open in iBooks" just below the tab you have open (at the top of the page).

From iBooks you can print them to a wireless printer easily.

Hope this helps.