2000 expitition clutch Problem

[cjmyers]

I replaced the shift shaft in my 2000 expidition 425 and have what I think is a clutch problem. I drained the oil, pulled the clutch case, and replaced the part. Replaced the gasket, put the case back on and filled with 5 quarts of oil. Engine runs fine but when I shift into gear it wants to go at first then it is like the clutch starts to slip. It feels like the shifter is going into all the gears and the reverse light comes on when I put it in reverse. I did not mess with anything other than the shift shaft when I had it pulled apart. If anyone has any idea what I should chech please help. Thanks.