What was found
YYC - ON TAKEOFF, AND GEAR SELECTED UP, GEAR DID NOT RETRACT AND LANDING GEAR PANEL SHOWED 3 GREEN LIGHTS, AND THE LANDING GEAR HANDLE HAD 3 RED LIGHTS. PERFORMED EMERGENCY/ABNORMAL CHECKLIST AND RETURNED TO FIELD. MAINTENANCE INSPECTED THE PROXIMITY SWITCHES, DOOR SEALS, DOOR MECHANISMS, NOSE GEAR, AND BOTH LANDING GEAR ASSEMBLIES. AIRCRAFT WAS JACKED AND THE LANDING GEAR WAS CYCLED SEVERAL TIMES. NO DISCREPANCIES NOTED. AIRCRAFT RETURNED TO SERVICE.