ADS error message-undefined model

hi,

I am a new user of ADS and i tried to simulate simple circuit, i have a diode in it and i get the error

"Diode1 is an instance of an undefined model1 "DIODEM1"

Also how can i put a vendor manufactured diode?

Any help is appreciated

thanks,
ramesh

ADS has a library, select a appropriate diode from this library..

i forgot to put the diode model thing on the schematic...