It could be a cable length problem, the standard A1200's IDE interface is unbuffered and might have problems with long cables. Officially only a 5cm cable is supported. Increasing the length of the cable the reliability decreases proportionally, which is why additional buffered interfaces have been so popular on the A1200.
That said sometimes it is necessary to cut the first wire (the red one) on the cable which carries the reset signal since some hard drives are too slow to start, and this might help improve compatibility with some models. So far I used many different drives with the A1200 including several Creative ones, so it is most likely a cable problem.
Although sometimes certain brands of hard drives are incompatible with other brands of CD-ROMs but that's fairly rare.
