squid proxy server

[David]

hi all,

i hav setup squid that controls 3 different classrooms.
each class has a range of ip addresses.

i hav used the acl as per documentation & help that every1 has given me.

acl machine src 192.168.10.21-192.168.10.41/255.255.255.0

but when i restart squid it generates the following warnings.

aclParseipData; WARNING : Netmask masks away part of the speified IP in
'192.168.10.21-192.168.10.41/255.255.255.0'

what is wrong??

thanxs a billion
DBH