water in rear storage compartment

[jwbups]

The rear storage, entrance side compartment, area is always wet. there is a rubber mat inside that compartment but the plywood floor is saturated with water. We emptied the compartment and dried all standing water and after todays rain it had standing water again. I believe the gasket is not on properly and we recaulked around the seam of the cover. Anyone else have this problem. thanks, Jim