i have found the problem.
When cfg usb loader starts it starts with cios 249.
I have installed cios 249 rev 21.
The configuration is:
247 base 56
248 base 57
249 base 58
250 base 37
When it starts it uses cios 249 so base 58 if i select 247 or 248 or 250 works correctly.
if i use config.txt the cfg usb loader doesn't work because doesn't detect the hardisk.
If i use only settings.cfg the loader works but it doesn't find the cover