Biceps are tricky...I get a lot of pain when I inject mine, so I typically stay away from them....unless I'm short on injection spots or just get some wild hair up my ass. Also, there are 2 spots on your bi's that can be injected, not just...why don't you see if you have better luck with the other spot. Also, if you want to be injecting your arms regularly, I suggest tri's...a little harder to pin but less pain IMO....also 3 spots you can hit on the tri.
BTW, spotinjections.com is OK but this site gives a much better view of everything IMO...no screw that, not IMO, they do IN FACT do a better job.
http://www.howtodoinjections.com/im.html