power steering whine?

i put new hoses new pump rack! i put the car in the air filled with new fluid. turned the steering wheel several times lock to lock. filled again started the car turned back and forth several times put lid on drove down the road and the darn steering still whines. took cap off let sit overnight. next morning started car sounded good so put cap back on went down the road after it warmed up started whining again. checked fluid and it's fine. I don't know what else to do. i flushed it, put new fluid again and burped it. let sit overnight again next morning same issue. what am i doing wrong? used atf+4 fluid?