Ok first question... do you know what the f of x2_4974_blue_f.bin stands for ?
It means that it will boot on the F partition.
You only have a F partition if you format it explicitly. That is probably why the dash is not found
at boot time.
Other question, why use 4974 version. It's a kind of old ? Why not use the last 4977 and modify it with xbtool if needed ?
Gabriel