401 error when calling a function of a published CodeUnit

Hello everyone,
I've got a problem when calling to a function of a codeunit published as a WebService. This is the past of the code where I call the function, and the error:



Have to say, that I have other codeunit published, and I execute every day functions from that CU, calling them from Console Applications, scheduled periodically in the server.

So, basically, the difference between the 2 scenarios, is that in the case that generates a 401 error:
1- I'm calling the function from a ASP.net WebApp instead of a Console application
2-The functions return a value to the app

Any hint about this issue?

Thank you very much!