Fabric softener doesn't leave the dispenser

The fabric softener doesn't leave the dispensing tray in my Bosch Washing Machine. I have pulled the tray out and cleaned the black gunk, but is there a particular cycle that I must use to have the fabric softener come into play during a wash? I tried Rinse Plus, but that didn't work. What other problems might there be associated with an error such as this?

Take out the drawer and clean the compartment and pipe at the end of the drawer with hot soapy water - washing up liquid works well. Clean all around it. To show this is working OK, put it in the sink and fill up the compartment with water until it is overflowing then stop. The water should drain out of the compartment on its own.

Next, where the drawer fits in the machine clean the water exit above the drawer with a washing up brush. This can appear brown or white depending on your water type. If this is OK try running the machine. If there is still a problem, remove the drawer again and turn off the power at the mains. Use something like a paper clip to poke all the holes in the water dispenser area above the drawer. There are lots of them so some patience might be required. If you live in a hard water area it could be blocked with limescale in which case an application of a descaling mousse or spraty will assist. Once complete, make sure you rinse the drawer area, drawer and put the drawer back in and run the machine on a short cold fill wash cycle. Put some fab con in the drawer to test that the machine drains it correctly. If all is well then there will be no fab con left. If it is still there then you will need to get into the water dispensing area to see what is wrong. Occasionally the mechanism can get jammed, lose a spring or just get broken, in which case it will need replacing.