You have to dig into the menu to make the remote available, you are
doing that right?

You need to be in Manual mode and I can't remember exactly when or why
but you'll occasionally get shutter readings all the way to 30 seconds,
then when you should get "bulb" you'll get "double hash" or something
similar.  Try tripping the shutter by the remote, remember there are
settings for 10 sec delay, 2 sec delay and immediate fire, then you
should see the "bulb" reading.  Don't forget to set the long exposure
toggle to keep the sensor from heating and producing excess noise.
Sorry I don't have the camera with me at the moment but when I get home
I'll run through it and see if there is anything else "odd".   I've
found the D50 manual to have a few shortcomings when reaching the
extremes of the camera's capabilities.  Download the D70s manual and
where the cameras have similar functions the D70s manual often explains
it in clearer terms.