the check engine light is on and the cruse control light gose on and off .
please i need to know whats wrong.

if the CEL is on then the cruise will not work, that's just how subaru works

If it's an '04, take it to the dealer and get it looked at.
Most common reason CEL comes on is people not tightening the gas cap enough, if that's the cause, the code will take about a week to clear.