I created a sp designer workflow that creates a library based on an event, with some specific format: YYYYMMDD-EventTitle.
The first time I did the workflow I did it as a list workflow and it worked fine. However to be able to deploy it to production I had to redo it again as a reusable workflow.
The reusable workflow works fine, but the document libraries are created always with the following format: 00010101-[eventtitle] and not correctly as: 20120325-eventtitle
Update1: I changed a little bit and put another log to history. TO see the result, please see the second image.