i'll try Bill's advice as i didn't see any other solution to my issue.
i'm not saving the document in web mode. i've tried to change the settings to be with 'none' thumbnail, opening sheet thumbnail, etc. nothing helped. the icon at the access point remain the same ('No Preview Available') no matter what i've at the settings....
i'll try to reload before putting it on the server and then from the QMC but I don't think it will help as changing it to opening sheet (for example) didn't result as an icon with the opening sheet