Surpising but a silly one!!!
Recently we had deployed one application in Production with five load balanced servers. We had a nice and clean batch file prepared and well test in Dev, QA and in Test environments.
When we tried to deploy the same set of solution packages using the batch file, all the solution packages were correctly added to solution store and deployed on to the respective web applications. BUT, FEATURE folders were created and also none of the DLLs were deployed into the target location.
After many trials, messing up with permissions for user etc, finally discovered that, the web front end (WFE) on which we were running the deployment script was not the primary server nor Windows SharePoint Services Web Application service was running on that server in the farm.
Seems silly, but it happens at the time when everyone is eagerly waiting for successful deployment and all eyes are pointed to one single farm administrator.
As soon as we changed server to the primary and reran the solution package, all went file and it was a smooth deployment (really!!!)