Transitioning a cube from a Windows environment to a Unix environment can be tricky.  Your cube may build perfectly in a local-build on Windows, only to give you errors like this in a server-build on Unix:

Start processing data source ‘My Data Source’.
Reading source data.
(TR3703) The user ID or password is either missing or invalid. Please re-enter the credentials.
End processing 0 records from data source ‘My Data Source’.

While it appears as though you have a problem with a data source in Unix, the real problem lies with your signon credentials.  Once you transition from a local-build to a server-build in Transformer, you need to have a valid Signon defined.  But when you do this, there is no way to test to see if your Signon Credentials will work – short of moving your Transformer model to the Unix server and building it.  If your signon credentials are invalid, you will get a message like the one above.

So check the Signon Credentials and that should solve your problem.  The apparent reference to your data source is a red herring.