Rules stop working after minutes!

I configured a lab with TMG 2010 evaluation very, everything goes well, now i have a strange problem, i configured a rule to block some web sites, and this rule added as number 1 rule, number 2 rule is two allow access to http and https, when i restart firewall service, users get the blocked pages blocked normally as expected, after few minutes users can open the blocked pages normally!!!! both rules schedule are set to always
when i tried to monitor a machine i found them bypass allow rule, without being stopped by the deny rule (no.1)

any help please ?