Gearbox problem after fluid change Help

[Dakes55]

I recently bought an A8 2.8 2002, and didn't have any service history with it, I have changed the multifunction transmission switch as it had the dreaded PRNDS lights on, after that job was done the car drove great with no problems, I thought I would do a service on the gearbox and change the ATF fluid and filter, but now I have problems, the gearchanges are not smooth, and I am noticing that the rev counter is moving slightly and not stable when in 5th gear, it feels like its slightly jolting, the fluid that was drained off was a dirty red in colour, with no contamination, just a very slight sludge build up, I fitted a new Meyle filter and gasket and filled the transmission with Febi Bilstein atf fluid 29738, this is clear/yellow in colour and according to Febi this fluid is the one for my car, I am concerned that this fluid maybe wrong, the service was carried out exactly to ZF specs, any ideas on this please.