Why transmission is slipping after you change fluid and filter?

I have chenged transmission fluid and filter and after it's completed, the transmission slips at about 30 miles per hour. I'm wondering if I did anything wrong. I put the right amount of fluid into it.|||sounds like there is not enough fluid in the tranny, check the level with engine warmed up and the tranny in park.|||You didn't say how old or how many miles where on your car before you did the trans fluid change. Sometimes if you wait too long and have too many miles on your tranny the parts are worn enough that the old fluid with some of the metal shavings and stuff in it is the only thing keeping everything moving right with the belts and gears and stuff. Then you go ahead and flush the system and remove all that garbage and put fresh oil in it and now you can feel that the parts are worn and slipping. I would recommend taking to a transmission specialist and have them look at it. Could be it just a minor tune up of some the components.|||You did not mention what kind of car you own. Chrysler, Dodge, Plymouth state right on the trans dipstick to check the level, hot, engine running and in NEUTRAL, not park (set emergency brake). Checking in Park will cause the level to be low and slip. Also, the filter needs to be identical to the one removed. Holes not lining up can block fluid flow giving the same result. A dented oil pan can restrict flow to the filter. Re-check that fluid level before you ruin your trans. Always read the dipstick for information about fluid type and special instructions.|||Let me guess, the car/truck has very high mileage. Assuming you put the correct type and quantity of fluid in it, sometimes putting new fluid in it actually flushes out crud that was helping old o rings seal, and now they are leaking and you lost pump pressure. You can try an additive but no guarantees. I have seen this happen many times with high mileage transmissions.|||This can happen if the fluid in the car was very old. It happened to me, then I tried various solutions (recheck fluid level, then try slightly overfilling, had a free check at a trans shop who said I needed an r%26amp;r). Finally tried 4 ounces of auto-rx and its been fine for 10k miles (160k now on car)|||what kind of fluid? if you dont use the correct automatic transmission fluid you will ruin your transmission and did you check fluid level in park or neutral with engine running|||Sounds suspiciously like not enough fluid.