I am guessing that you have encountered two of the most possible errors:
- "Invalid expand expression"
You may need to check whether the expand expression is a valid JSON
object, either URL encoded or not.
- "Filter and Sort are not allowed when expanding multiple items"
You may need to check whether you are not using a filter in the expand expression to tailor the expanded data in regard to the limitations outlined here
On the other hand, you can use the standard X-Everlive-Filter header to supply a filter to tailor the parent data before expanding it.
I hope that this helps.
Telerik by Progress