CRM 2013 Javascript set lookup value problem.why?

Hello experts,

I am using crm 2013 orion server .in that i am using one javascript for xrm.page  to set lookup value .i am using as crm 2011 

but the lookupvalue is not populated to corresponding field.it was working in polarisversion .but what are changes in xrm model ,I got no error in my script.but what might be the reason for not lookupvalue is not set.

thanks and regards

Murali