Exporting problem with instances in a pixelfont with multiple cap-heights

i am working on a pixel-component font with multiple masters that have different cap-heights:
When I want to export the font it says my instances are not configured in the right way.

But i dont really work with instances in that font, only with masters. How do I configure the instances right or is the problem in the different heights of the masters?

Thank you very much for a reply,

What you export = an ‘instance’.
Go to Font Info > Instances. Delete all instances, and then regenerate the instances for each master:

And set up all masters correctly. each master needs at least one different value in the weight/width/custom fields.

Problem solved.
Thank you very much!