The attachments only work if your BB Perl OS is 18.104.22.168 +. I know mine was 22.214.171.124 and it was not working but now that i've updated to the latest I am able to attach pictures from my SD card or stored on the BB.
Actually, the OS has supported picture attachments since 4.2.0. What didn't support it was the BIS system and BES had to be 4.1.3 and up. The reason it worked for you after you upgraded was that it sent you updated service books for the BIS.
I could be the service. I live in an area that has patches of bad service and if I am in the middle of sending an email or text it won't go through. I usually have to re send before it will finally work