Let me first say that I am a Windoz programmer but I think I can give you some suggestions none-the-less.
1) Is nkj(ipar) == 0?
(i.e. is your do loop only 1 iteration)
2) In the do loop insert diagnostic code to display the omp thread (team member) number and value of i.
(i.e. assure each thread is performing ~1/2 the work)
3) Assuming multiple iterations and multiple threads are working, next see if the F77 code is calling runtime library functions that are OpenMP safe through serialization locks.
I do not know if the documentation list the serialized OpenMP safe functions/subroutines but a short list includes
READ, WRITE, RAND, DRAND
4) If both threads are running then check to see if they are being forced to run on the same core. (Check on options relating to thread affinity).
Don't trust your first glance. Insert diagnostic code to verify what you see is what you have. More often than not, diagnostic code exposes false assumptions.