Sam Pennisi

I have a 2010 Chevy Express 2500. Bought it for a conversion. It leaks when i t rains and pools on passenger side floor. It appears the water was coming from the corner of the windshield where it meets the metal frame. There was a hole the size of a dime. I removed the windshield plastic edging and found algae/mold. Sealed the hole and caulked along side the windshield between body and glass as far as i could. Rained the next day and found more water on the passenger side leading me to believe the caulking forced water backup . The leak was not dripping but dropping from the interior where the ceiling finish and corner moulding meet. Is it possible that water is running in from the gutter on the van roof. Another thing Im not sure of: is the rain gutter on the roof formed by the design of the metal roof? could this be a weak point where the water could find a way through? If there is someone who has experienced this or similar type of water issue I would appreciate your fix or recommended fix.