Helmatin or Helmaprene are the only adhesive to use with vinyl.
Vinyl contains a placticiser that will attack regular glue and turn it to mush.
Make sure the glue is evenly applied to both parts, and thoroughly dry before sticking the parts together. You have up to 24 hours after the glue dries, and it will still be heat activated and stick better than Wile E. Coyote's Acme products.
Methelene Chloride can be used to thin it if it's a bit too thick for a nice spray, available at most janitorial supply houses.
BSC Chemicals on Cyrville for Shon