A few things:
1. Make sure the partition is below 4Gb (ie 4096Mb), make it smaller may help.
2. Does the drive spin up in time for AmigaOS to see it. If not then cutting line 1 in the IDE cable may help or install kickstart 3.1
3. Do you have enough power to run 3.5" drive. Do NOT use the 23W PSU with the A1200.
4. If you like try other Filesystems such as PFS3 or SFS instead of FFS.
