cub cadet pto problems

bought a new pto for my cub cadet 1050 it will engage run for a few seconds and quit ( disengage ) put on new key switch , pto relay , and pto switch. What next checked wires and all seem to be ok any ideas because I am out of them . Thanks for any help !!!

Pto clutches can be sensitive to battery voltage changes. Have seen batteries that would start the mower, but wouldn't engage the pto. Replace the battery or install jumper cables and it will operate fine.