I really need some help, please!

I'm in the Vale of Shadows, but i can't seem to get the lever in the lower tomes to open the door to Kresselach. I have 5 keys. How many am I supposed to have? I got 1 key from 4 of the crypts, plus a fifth key from inside the lower tomes. So why isn't the lever opening the door when I pull it? Is there something else i'm supposed to do?
If anyone can provide any help i'd really appreciate it, cause i've been stuck here for way too long and it's getting seriously frustrating!

Thanks

Have you killed all the baddies in the tombs to the left and right of the lever, as well as those close to the door? I missed those and was similarly stuck for a bit, but once I did them in, the door opened...

I do not think you need keys for that. Make sure you cleared all crypts and all rooms in this particular crypt before. You can compare your progression with the maps showed on this web site. This can reveal some areas you have not cleared yet. Hope it helps.

To operate the switch, you have to find (and carry) the Black Wolf Talisman, found in one of the side crypts. It sort of functions as a key. It's a rectangular gray stone with a pawprint of a wolf painted on it in white. It has magical properties as well, a good item to wear.

There are altogether 7 keys, counting both the talisman above and the Holy Symbol of Myrkul (which allows you to open the north door on the first level). Presumably you have the holy symbol, so the talisman is the only one you're missing.

Fortunately, this is the only dungeon where you have to scrounge for a lot of keys.