NAS error

hi all, I’m trying to discover the commerce portal. It run for 3 days. but now I get an error when I trying to do an action(subscribe, showing transaction …) the error message that I get is: “no response from Navision.” [xx(] [xx(] [xx(] [xx(] I think that the error is linked to the NAS. in the event viewer I don’t get any error [V][V][V][V] any one have an answer thanx