Adding a chart on a custom page, using checkbox as x-axis

Adding a chart on a custom page, using checkbox as x-axis

Hi,

I'm a bit confused on how to use the checkbox fiels in a chart. It seems impossible to use it.
I have set a checkbox fiels with 4 entries, which are basically 4 steps for a record (they might not be dependent from each other)
I'm trying to create a chart (it can be another type of widget), which displays for each checked entry in each record, how many records have this states... Apparently checkbox fields can't be used in a chart ? Am I right ?

Checkbox entries as x-axis:
- option 1
- option 2
- option 3
- option 4

y-axis : number of records having the option checked, for each option

Any idea ? Or should I proceed differently ?