Water Leak in Trunk of my 2000 Deville DHS

[2000_DHS]

I got a water leak in the trunk of my 2000 Deville DHS. Has anyone ever had this issue? the water is leaking in thru the top right side. I took it to the dealership several times and there were pretty much no help and assisted me to throw away several hundred dollars. Is it the weatherstrip? someone please help me out, thanks......J