[otrs] problem: no sla selecting service

Hi to all, I would like to explain my problem with OTRS 2.4.4 and ITSM 1.3.1. I make a new installation of OTRS 2.4.4 and ITSM 1.3.1, I create service, sla associated to the service, customer user and set default service. Now I try to create a new e-mail ticket but wen I select the service no sla is loaded. But if I create a phone ticket it works, the slas are loaded. If in email ticket i create the ticket without the sla (I can't select it!) and then I modify the itsm fields in ITSM-fields page i found the right slas. I have this problem even with OTRS 2.4.3 new installation and also after a migration from otrs 2.3.4 and itsm 1.2.3. What is wrong?? Any help is appreciate. Regards. Francesco.