Please enter a valid Network Address

Having problems getting some networks into OpManager. Sometimes I get the "Please enter a valid Network Address" error on the web admin page, but it works in the client Discovery Settings page, but now it's not working on either. The client window appears to input and accept the networks, but they don't "stick." I go right back into the window and the changes I made aren't there. The networks I'm trying to input are 10.254.0.0 / 255.255.255.252; 10.254.0.4 / 255.255.255.252; through 10.254.0.16 / 255.255.255.252.
I tried just putting in the 10.254.0.0 / 255.255.255.0 network to cover them all (which would go into OpManager), but I'd get a device or two or ten showing up on what would be the network or broadcast address for the .252 range.