Current Source Circuit - Simulation file included

hi everybody,
I'm working on a Current source circuit that I found its design on the web, here is the design :
**broken link removed**

the problem is that the current levels in the simulation - run by Multisim - is very lower that the ones in the original design (0 - 100 mA controlled by voltage.
so I wish I know why and how I can modify this circuit to get my desired levels.
and how can I analyze this circuit ? and should this circuit give me practically precise values ?
thanks in advance, any help is ppreciated.

circuit file : Circuit1.ms10

Did the orginal circuit try to run the current source on only 5V? The threshold of the 2N6804 is ~-3V. The LM2904 is not rail-to-rail out, so I'm guessing that the FET is not turning on. This circuit might have a hope of working if operated off 15V.