Simulating OpAmp in Simulink: Error Fix Needed

[jean28]

Homework Statement

I need to simulate an OpAmp in Simulink but I can't seem to find an OpAmp block that works in SimPowerSystems, so I kept searching and found out sort of an equivalent. However, the simulation still gives me an error. I would highly appreciate if anyone could tell me what I could do to fix it.

The Attempt at a Solution

Here is what I have so far:

http://i1226.photobucket.com/albums/ee410/jean28x/Projecto2.jpg

 

[jean28]

The OpAmp equivalent is the part where I put the two voltage measurements followed by the adder block, and then the gain and saturation blocks.