Whether or not that this is a bug is certainly up to Cryptic Studios.

I am currently I am Lt. 12 and have put 6100 skills points into both myself and my Bridge Officers, yet I have not been able to rank up to Lt. Commander. Two friends of mine were able to achieve Lt. Commander without any problems yet I am. Hope that this can get fixed for anyone else that is having the same problem.

Signed,
KBrown24