thx, how stupid of me not to see this.
OK, to summarize:
1. I changed to /bin/bash and now it works fine.
2. I copied the script back to my FAT32 partitions and .... it doesn't work there ! ?
Appareantly it is not a good idea to start executing scripts on a FAT32 partition, it is just good enough to shuffle files between my Windows and Linux OS.
Thx again for your support.