One other issue here....
You need a PIP/Pegasus FMC...
and you need a symbol generator of sufficient newness....what I mean is that the original generation symbol generators will not draw the circle on the display and in fact can cause the EHSI to fail....if that happens all one has to do is remove the fix from the fix page and EHSI functionality is restored.
So it is a combination of the FMC and symbol generator...
cheers