Problem with Proteus Simulation of Buck Boost Converter - please help
The reason you have no current on the output is because you don't have a load that will draw any more. 

As it stands, your load consists of R4, R5 and R7 in series. R7 is 100 Ohms, R5 is 12.9k and R4 is 1.5k. Add these together for 14.5k.

Now use Ohm's Law of V=I*R and re-arrange to solve for I - I = V/R. Plug in the numbers and you get I = 12.3/14500 = 0.000848276, which is pretty much what you have there.

Looks to me like your simulation is working properly.