Using REST2.0 API with LDAP users

I’m trying to integrate RT into our workflows better with the REST 2.0 API and for the initial testing period I just want to set up http basic authentication so that I can work with the API a bit. My users are imported from an LDAP server.

If I try authenticating as a user imported from ldap, I just get the following message: {"message":"Unauthorized"} and a message in the log saying Failed login for user

If I try authenticating as a user created in RT, such as the auto-created “root” user, this succeeds.

Is there any way for LDAP users to be able to call the REST API without using the Authen::Token plugin?