904 Help please

My 904 doesn't want to shift into second until about 30 or so. It doesn't slip or leek or make any funny noise its just that the car is reving pretty good before it shifts. If I haven't given enough info its because I don't know a lot about automatics so please ask if you have any questions.Other than the shifting issues it seems fine. What do you think and how do I fix it. Thanks for the help.