I second Benz's diagnosis. There is a black plastic clip that slides into the metal bracket from the bottom and it holds the plasic piece that is attached to the cable to the metal bracket. Without the clip the plastic piece will slide out of the metal bracket. Look for the clip or pieces of it at the bottom of your door panel... maybe you can reuse it if you can hold it in place with a little silicone or something like that.
1993 190E 2.3
2000 Toyota 4x4 Tundra