Originally Posted by kalutika
Epoxy comes in two parts that need to be mixed to actually activate. If you are just using one part it won't harden. Devcon 5 minute should have a solid bond in 5 minutes. If you can still pull it apart by now I would suggest doing so and following the instructions that should be on the bottle for clean up unless it involves heavy solvents of any kind. Clean it thoroughly and get some superglue.
I recommend gorilla glue, I use that stuff like duct tape.