Subdivision Surface with a hard edge problem

Hi.

I added the side of inside sink later and sub surf causes problem. even if I put loop cuts to align the lines(vertical side) it doesn't help.

https://blend-exchange.giantcowfilms.com/ doesn't work for me so I leave the file in google drive address. https://drive.google.com/open?id=1hqZDeiltItw2UUwfPcbUuI6SbGw_IiKi

Thank you
I can't seem to open your file, but from the pictures you've provided, I tried to recreate the problem and possibly solve it here:

https://youtu.be/S1x6OycmPD0

In the video you can see me going inside the mesh to check if there are any faces on the inside. Make sure to remove them if you see any on yours. Then I select all and clicked "Remove Doubles".

Let me know if the problem persists