Fortress key

I have completed the Find the Key quest. I have a red fortress key in my inventory, but I cannot enter the Fortress of Glass. I get the message that I don’t have the right key. Help please.

The key you need is the Glass Key. You get that from King Locrinus, which you must have done to finish that quest. Did you drop or stash it?

I had unknowingly stashed it! Thanks so much!

It happens all the time. ^^