Alternator indicator trouble

[rusty1c]

I purchased a Proform 66438 alternator on line. It is installed in place of a generator. There are three terminals that are used for this application.
The white wire---- goes to the generator charging light
The red wire-------goes to a hot wire when the ignition is turned on.
Main terminal------goes to battery positive.

The problem I am having is that the first time I turned on the ignition the generator charging light came on and then it went off as soon as the car was started. Which is how it should work.
The next time I went to start the car the generator light did not come on. I checked the generator light circuit all the way to the end of the white wire at the alternator and it was hot as it should be.
I unplugged the green plug on the back of the alternator and grounded the white wire and the light came on.
The light bulb is good but the generator light will not come on prior to the engine being started.
On the back of the alternator I measured the terminal which the white wire goes to. The terminal on the alternator measured 256 ohms of resistance to ground. It would seem to me that this terminal should be hard grounded when the alternator isn't running. This would allow the light to be illuminated when the ignition is turned on and then when the alternator is running it would build up voltage and the light would go out since there would be no difference of potential. When the alternator is running it is charging at 14.57 volts so I know it is operating correctly.
Is there a problem with the alternator light circuit?
Thank you.
rusty1c