What was found
AT APPROX. 1540 LOCAL TIME, N750JM DEPARTED KHOU ENROUTE TO KCMI. WHILE CLIMBING THROUGH 8,000 FT, THE PILOT NOTICED THE CABIN CLIMBING WITH THE ALTITUDE OF THE AIRCRAFT. THE FLIGHT CREW PERFORMED THE CHECKLIST ITEMS FOR CABIN NOT PRESSURIZING, AND LEVELED THE AIRCRAFT OFF AT AROUND 10,000 FT. CREW WAS UNABLE TO MAKE THE AIRCRAFT PRESSURIZE. CREW ELECTED TO RETURN TO KHOU AND LANDED WITHOUT INCIDENT. TROUBLESHOOTING OF SYSTEM IS ONGOING.