What version of Mandrake and kernel are you using?
You can not use /dev/hdc as the device.
Assuming you are using 2.6 kernel to find the device ID:
cdrecord dev=ATAPI: --scanbus
Then use the answer to as the device. example:
cdrecord dev=ATA:1,0,0 whatever.iso
With a 2.4 kernel assuming scsi emulation has already been configured
To burn example
cdrecord dev=1,0,0 whatever.iso