my dogs get along till my lab gets close to me

Question
i have a  2 year old beagle and a 11 year old lab mix and everytime we  start petting our lab my beagle attacks him we tried pinning him up for a while and hitting his nose  but nothing seems to work and we don't no the problem
(when he attaks he won't let go of the lab and he makes him bleed.)

Answer
Neuter him if not already.  You certainly don't want him ever passing on such behavior.  

The key to most behavior problems is approaching things using the dog's natural instincts.  Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog.  Life is much easier if the 2 legged pack members outrank the 4 legged ones.  You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at http://www.dogsbestfriend.com/  For more on being top dog, see http://www.dogbreedinfo.com./topdogrules.htm

If the above still isn't enough, you may need a private trainer.