I am not exactly clear on what you have configured. But the "preview" option in SSIS is very simple. It does not work with complex use cases. Just because Preview doesn't work, does not mean it is not configured correctly.
FYI, although it is possible to read this type of file in SSIS, I always read these files into "stage" tables with columns defined as the main rows, and then use TSQL to parse the header/footer out of the data. It is much easier to code and to deal with in TSQL.