Nikon Speedlight Problems?

I have a speedlight SB28 DX on a D 50 camera… Problem is that it'll only fire on A or M or 3 little lightning strokes… Everytime I put it on TTL my camera won't fire… On the camera the ISO is on Auto so difficult to set.
On the flash I have to SET 400 ASA to get a reasonably exposed photo… Read all the blurb on the the Speed light… Gettin' complicated… Which setting do I use so that it all goes smoothly and I don't have my head full of figures eveytime I shoot a Photo A or M or TTL ( with something i missed?)

I don't think your flash is compatible in TTL mode with the D50. I did a brief web search. I use a SB-15 with a couple Nikon DSLRs and have the same problem. The older flashes only work with a few select film SLRs in TTL mode.

However, if you fix the ISO and put the camera in manual mode, you can leave the flash in AUTO and it will expose with little difficulty.

Look on page 110-112 for more information on using your SB-28 DX.

NOTE: "The D50 is not included in the "digital SLR" category in the SB-80DX, SB-28DX,
and SB-50DX manuals" -- page 112

Your SB28 DX is a so-called D-TTL model, the very first flash metering system (actually an adaptation from the earlier SB28 non-DX speedlight) for Nikon digital cameras, such as the D1, D1x, D2h, D2x(s) and D70(s).It's a very early digital flash metering system, and not very reliable, even when used with cameras that were actually designed to work with D-TTL.

Your D50 however, relies on Nikon's newer i-TTL flash metering system which is Nikon's current system. As you've already found out, it will only fire on A and M(anual), and even then will not be accurate unless you tweak the camera's settings. Of course you could buy a current i-TTL equivalent such as the $300 SB-700, but maybe you can find an older, second-hand i-TTL speedlight such as the SB-600 which has more or less the same output as an SB28 DX. Another alternative would be a non-Nikon i-TTL compatible brand such as Metz or Sunpak, which are generally a lot cheaper.

Your D50 is an iTTL camera, this means the SB28 DX won't talk to your D50. With older flash units it's much simpler to go manual.

Due to the way flash works, you should run in manual mode on the D50 and fix your shutter speed to 1/500 (D50 is an odd case of very high flash sync, in manual flash exposure it's unlimited, so 1/500 is nominal), set your ISO to a sensible value. Then set your aperture for the desired effect. Go to the SB28 and set it to A mode and input the aperture and ISO speed to match, and use the zoom setting to select the focal length you're using (remember to convert for DX sensors), this gives you an automatic flash exposure, but without TTL metering. Essentially this is similar to the old fashioned auto flash setups.

Realistically, this method is so complicated you may as well run both devices in M mode. Usually set your camera to 1/500, ISO200, f5.6 and then use the power control on the flash to adjust exposure. You'll probably have to meter a few times, but after that you can just flip between the various flash settings.