RWS 00058 Error

I can get report and element details but unable to get report structure. Getting below error. Tried different documents but still getting same error.

http://ip:6405/biprws/raylight/v1/documents/6094/reports/2/specification

<error>

    <error_code>RWS 00058</error_code>

    <message>Not acceptable, (RWS 00058)</message>

</error>

Appreciate any help.