If you create a new primary after removing the current one you first need to format it before you can use the SYS C: command. You can generally see the dos files transferred automatically by simply using the FORMAT C: /S command from the A:> dos prompt while on the floppy.
You can't run any commands from the C:> prompt without at least the dos systems files already on the drive. These are used strictly at the A prompt to see the drive formatted and basic dos system files transferred. With the old primary removed you now use fdisk to create the new primary first then see that formatted with the dos command. The error message is simply from trying to transfer system files onto a now unpartitioned drive.
You can't run any commands from the C:> prompt without at least the dos systems files already on the drive. These are used strictly at the A prompt to see the drive formatted and basic dos system files transferred. With the old primary removed you now use fdisk to create the new primary first then see that formatted with the dos command. The error message is simply from trying to transfer system files onto a now unpartitioned drive.