You could be performing the exercises incorrectly or you may have a blockage in that area. Try this Qigong method to clear it;
1. Inhale, hold breath and pull the root lock2. Tongue on the roof of the mouth3. Rub your hands together till hot4. Visualise energy rushing to your hands5. Start massaging the spleen area
Perform steps 1-4 at the same time then release it all and start massaging the spleen area until you are satisfied.
You could also work on your Sacral chakra also.