Sorry for the delay in getting to your question.
There are several things can cause this.
The control for the machine, the inlet valves, the dispenser top and the dispenser drawer can all give a problem in the conditioner not being taken.
Some of the following you may already have done but it's worth going through it all to double check.
Take the drawer out of the machine.
Take the cover on the conditioner compartment off.
Clean out the drawer and the tube in the drawer.
Clean out the tube in the cover you took off
Refit the cover, refit the drawer and try the machine again.
If the drawer and syphons are clean and clear, and it doesn't work, then the problem lies deeper.
Take the drawer out.
Look into the dispenser and up.
Give the holes a good scrub (the ones that would be above the conditioner when the drawer is closed).
Use a length of garden tying wire or garden strimmer wire to poke into the holes and along the water ways as far as possible.
Once you've cleared the holes, try the machine again.
If still the same, you'll need to take the dispenser out and clean out the waterways.
To take the dispenser out of the machine :-
Unplug the appliance.
Take the top off.
Take the screws holding the dispenser in place out.
Take the hoses attached to the dispenser top off.
Unclip the dispenser top.
Push the tub down as far as possible and pull the top out rearward.
(it does come out this way, we do it on a regular basis).
Clean the dispenser top under running water, ensure water gets through all of the holes.
Refit the dispenser top, reassemble the machine.
Try it again.
If it still fails, it can only be the inlet valves or lack of water flow to blame.
Check it out, see how it goes and get back to me if you need more help.
Hope this helps