VerifyPassword function performance

Hello, dear colleagues!

I need to implement extra authorization besides standard Lotus ID for one Lotus database. User credentials are stored in another Lotus base, and each pair contains Login and Password hash not the password itself. I use VerifyPassword function like that:

session.Verifypassword(PassStr,HashStr)

According to Lotus Help function arguments should be password itself and original hashed password so VerifyPassword checks whether this password may be hashed to such result. I am absolutely sure about entering correct credentials.

Please help!