"Fill beans" always showing on my Z5?

Hello, I hope someone can help me solve my Z5 problem. When trying to
make coffee, 'Fill Beans' comes up in the
display and it then aborts the coffee making process, regardless
of how much coffee is in the hopper.

The grinder, hot water and steam all work, and it makes all the
noises from the brew mechanism.

Is this a serious problem or can it be resolved easily without too much
expense ?