VLSM ! is it supported by packet tracer 4.0

hi, am doing a case study of ccna sem3, and will doing it i got this messege:

ADMIN(config-if)#ip address 223.0.0.64 255.255.255.240
Bad mask /28 for address 223.0.0.64

Its because of VLSM but does version 4.0 support it?

223.0.0.64 is the subnet address isnt' it? Can't assign it...

the IP 223.0.0.64 has all zeros in the host bits when you use a mask of /28. You con not assign such an IP to an interface. Try this IP: 223.0.0.65

or change the subnet mask to 255.255.255.128