An Error During the Simulation

Hello, i am both newbie in this forum and OrCAD. I need to simulate the circuit as shown below but i have a problem in Pspice:

INFO(ORPROBE-3183): Simulation running...

** Profile: "SCHEMATIC1-Full-Bridge"  [ D:\Electrical & Electronics\Power Electronics\Simulation & Schematics\Orcad\full-bridge-pspi

Reading and checking circuit

ERROR(ORPSIM-16276): Can't find library

Circuit has errors ... run aborted

See output file for details

INFO(ORPROBE-3188): Simulation aborted

I am using UC3825 but it also says as follows:

WARNING(ORNET-1018): Connection to unmodeled pin U8 pin 'RT'

WARNING(ORNET-1018): Connection to unmodeled pin U8 pin 'CT'

 Schematic: http://oi62.tinypic.com/qrdjzo.jpg