Error 21920355: Grade (27502) is a required field.

For graded trading cards in the specified category, the grader and the grade are required to be specified through separate ConditionDescriptor containers. Numeric IDs are used, and these IDs represent Grader, Grade, and their values. Below is an example of what that might look like: 27501 275010 27502 275020 Key : 27501 : Grader 275010 : Professional Sports Authenticator (PSA) 27502 : Grade 275020 : 10 (grade of 10) The getItemConditionPolicies method of the Metadata API can be used to retrieve all condition descriptor numeric IDs for a category.