Problem With Nested Try Catch Blocks In SQL 2005

hi All,

Code:

begin try

begin transaction trans1

//some transaction

begin try

begin transaction trans2

//some transaction

//Raise Error

//commit transaction trans2

end try

begin catch

//Raise error

end catch
//some transaction

//commit transaction trans1

end try

begin catch

//Rollback trans1

end catch]



In the above code when an error is raised in the transaction trans2 the immediate catch is not invoked where as the outer catch is being invoked. I dont know y?. Can anybody help. Thanx