Hi,
This error is returned when the API call is using incompatible/invalid element. AN element with incorrect case is also considered invalid. Ex: For the SAINT server, 'product' is valid, however, 'Product' is invalid.
Please check for the valid elements to be used via the 'getCompatibilityElements' method and update your call. This should help resolve the issue.
In case the issue persists, it'd require further investigation and I'd request you to create a support ticket by contacting Customer Care for the same.