What was found
CRUISING AT FL 260, THE ACS LOW INFLOW CAS MESSAGE APPEARED AND THE CABIN ALTITUDE CORRESPONDINGLY BEGAN TO RISE. WE REFERENCED THE QRH AND ALERTED ATC THAT WE NEEDED LOWER. THEY INITIALLY GAVE US FL 240, AND AFTER A LITTLE PRODDING GAVE US 17000. BY THIS TIME THE CABIN WAS INCREASING THROUGH 10,000' WITH THE CORRESPONDING CAS AND AURAL ALERTS. WE DONNED OUR OXYGEN MASKS, DECLARED AN EMERGENCY AND WERE CLEARED DOWN TO 10,000. THEN INSTRUCTED OUR PASSENGERS TO PUT ON THEIR OXYGEN MASKS. THE CABIN ALTITUDE MAXED OUT AROUND 12,300'. AFTER LEVELING AT 9000' WE WERE ABLE TO RESET THE SYS WITH THE QRH BUT COORDINATED WITH ATC TO DIVERT. ON VECTORS TO DIRVERTED DESTINATION, WE RECEIVED AN ECS FAULT CAS MESSAGE. AT THAT TIME WE ELECTED TO DIVERT TO ANOTHER DESTINATION. THE FLIGHT WAS UNEVENTFUL FROM THAT POINT FORWARD.