if you DIY, it is better to purchase

the automatic fluid from the dealer with your VIN to make sure the correct fluid is used.  If you used wrong fluid, you need to have the transimission system flushed, not just drain and pour.

 Also check the fluid level. The fluid level might be too low. Unlike the motor oil level, the transmission fluid usually should be checked when engine is idling and the transmission was shifted to P, after all gears(P,R,N,D....) have been selected once.

Personally, I felt that "drain and pour fluid every 30,000 miles" is the minimum maintanance for a transmission system.