Thy do not fail, they are teling you that they cannot find any partition table in the first sector of the (hard disk) image hence they cannot imagine/guess a HS geometry and then default to 255/63, they are warnings, not errors.
both lines fail with:
Autodetect number-of-heads failed. Use default value 255
Autodetect sectors-per-track failed. Use default value 63
Does the command need more parameters or this is just information of what is used ?
An error in grub4dos normally has the format (as the one I posted earlier):
Error 61: refuse to hook int13 because of empty drive map table
Error <errnum> : <error description>