I was not able to test it just by the information that you provide, although I have some clue what is wrong:
fieldValue is 0, no entity will return a cart for this value.
If you are performing the request for guest user you can check the table
quote_id_mask but the
fieldValue must be a hash. For logged users
fieldValue needs be an int greater than 0 and that is the entity_id for
Can you share which Magento version are you performing?
I had a similar problem using Magento 2.1, therefore include that information might be relevant.