"Page header or footer longer than a page."

As the error message describes, the report cannot generate because the Page Header or the Page Footer is longer than a page, therefore it can't fit it all onto a page, and it's supposed to display this on every page, so your report would be infinitely long and every page would be identical.

Usually, the problem is something like you're listing all the service providers you selected for parameters in the page header, and you selected a lot of them. Or you just have too much information in the header.