disinfecting water supply

HELP URGENT
We are travelling to Spain next week. I can't get the disinfected water to come through to the van. I had the pump on internal , external and then both fill; water fill on and off. The hose was submerged in an aquaroll with puriclean next to the van but the pump wouldn't work. However it did work when connected to mains water.
Now will just have to chance it and drink bottled water over there but would be grateful if anyone can help for next time. (Not taking aquaroll with us.)
EDIT
Sorry folks, no need for replies
Have just reread ALL the whale fill posts and it looks as though we will need to buy an external pump. I think prev owner kept his as some people say that one was supplied with their van. Our prev owner also took all the crockery, glasses, TV and lampshades. He only had the van for 9 months !!!

If it working when set to both and the main water fills, that means the solenoid cut off valve at inlet is opening ok also power is going to the internal pump so thats good.
On the sergant unit if it is an EC325 there will be 2 fuses both 10Amp one for pump 1 and one pump 2. Test these fuses one may be out. Then test you have power outside when you have selected fill for the external pump. If you have power the external pump may be faulty so this may need tested on its own.
Hope this helps if any other questions ask away