In COT, chapter In The Night, I've found something strange.  Avi and Egwene are meeting in TAR, Avi coming in place of Elayne.  Here is the issue :

 

"She could not make this work," Aviendha said...as she touched the twisted ring that still hung from it's strip of leather..."The flows kept slipping away from her.  It is the babes."

 

The ter'angreal they are speaking of requires no channeling.  So what's the deal? 

I noticed this as well but it's not the twisted stone ring she's using.

 

The ring she is talking about is the one that was recovered from Ispan Shefar when she was captured in Ebou Dar. 

 

It is a silver ring that puts you to sleep and then brings you into TAR.

 

Good catch though.