Unable to find all Elemental Stones!

I was farming sewers level in Kurast bazar/upper kurast for elemental stones. I have played like 30 times but am unable to find the light stone. I got all the rest stones but am unable to find light stone. Is there any way or any particular location or is it just I have to keep farming until I find it?

Am trying my hard luck since two days but no use

continue farming.......

Yeah I got it finally. But a problem again.
I have transmuted all elemental runes to get Kabraxis' Stone rune. Now when I transmute Kabraxis' Stone rune with other 6 elemental runes to get token of lies,, its not working. Its not transmuting into the token of lies. Please help! Whats wrong?

Are you sure you doing it with right character(sorc)?

 only for sorc??
Am so dumb that i don't know that.
Am trying with my Amazon character. But token of pain did worked for me. Why not others?

Every character can create just own token, paladin haven't any tokens.

Dimitry can you please elaborate.

Can I make Valkyries prime for my amazon character? If yes, please tell me the procedure.

Pain (Amazon)
Lies (Sorceress)
Terror (Barbarian)
Destruction (Necro)
Suffering (Druid)
Hatred (Assassin)

Each of the tokens must be created on the corresponding character.
You'll need at least 2 of each token (one for Valk Prime, other for Laz's book upgrade)

Check the v7 documentation for more information.