NAV 2015 access ODATA from external application error 401

Hi, I need to access data through NAV webservices from an external application.

This app runs in PowerBuilder and I can connect to NAV with http://x.x.x.x/SKN_TEST_001/OData using Windows Authentication.  

But on some tables I need to access data by company, if I create the connection using 

http://x.x.x.x/SKN_TEST_001/OData/Company('companyname')/  I receive an error 401 for authentication.

Any help on what to check?

Best Regards

Alfredo Santibáñez