SP.SOD.loadMultiple Issue

I am trying to load the project context in order to access some data. I am using the SP.SOD.loadMultiple function as follows:

SP.SOD.loadMultiple(['sp.core.js', 'sp.runtime.js', 'sp.js', 'ps.js'], DoSomething());

function DoSomething() { alert('x'); }

If I remove 'ps.js' everyting works fine, but I won't be able to access project context.

I've checked and the file exists in the server: server_address/PWA/_layouts/15/ps.js

Someone knows what may be the problem here?

Thanks