Why won't /etc/swapon work?

[wcs at hou2b.UUCP]

I have a 4.1BSD system on a VAX 780 with multiple RM05's.
I have the files /dev/hp0b and /dev/hp3h defined in /etc/fstab,
but when I try to do /etc/swapon, it claims that it can't find those
devices.  My config file does have hphp defined.

Where should I start looking?   Thanks.

				Bill Stewart hou2b!hoscf!bin or
					     hou2b!hoscf!bill
				BTL-HO x0705