Unable to add WCF service in asp.net Project for implementing Polling Duplex service using silverlight

Hi all,

I m using WCF duplex service to implement Push notifications feature like getting records from database without refreshing it..

Same thing working perfectly fine in Silverlight Application Project..But when I m embedding it in asp.net website 2012 it gives error that

"configuration file is not a valid configuration file for wcf service library" and roll backs the changes..

web.config that allows to add pollingDuplexHttpBinding element in binding section..I m new to WCF so that have much idea..a

same explored many solutions but nothing is helpful..anybody having gud idea please reply back...