Updating custom Jira field does not work using Jira Rest API. What am I doing wrong?

I am trying to update a custom field in the Jira issue using Rest API. Below is my command line for updating the “Problem ID” field for my Jira Issue:

curl -D- -u userID:PW -X POST --data ‘{“fields”:{“Problem ID”:“dummydummy”}}’ -H “Content-Type: application/json” https://jira.corp.adobe.com/rest/api/2/issue/DCMAF-1

The above command did not generate any error, but it also did not update the “Problem ID” field for DCMAF-1 Jira issue with “dummydummy” string. Can someone help me check to see what I am doing wrong? I verified that the User account that I am using has privilege to update the Problem ID field via Jira UI.

The custom field that I am trying to update is a single string field.

Thank you;

I figure out what i am doing wrong. I need to use the custom field ID and not value and that did the trick.