And just so that there's no confusion, the National Serials Data Program (NSDP) and the US ISSN Center are the same body.  They use both names on their website <www.loc.gov/issn/>

Steve Shadle/Serials Access Librarian  *****  shadle@u.washington.edu
University of Washington Libraries      ***     Phone: (206) 685-3983
Seattle, WA 98195-2900                   *        Fax: (206) 543-0854

On Thu, 14 Jun 2007, Barbara Pope wrote:

> Hello, Bobby.  I always check the Worldcat record.  With the really
> un-solveable ones, I generally email the National Serials Data Program.   I
> have found that even when NSDP assigns a new issn, that the publisher does not
> print the new number on their issues.  Generally, NSDP gets back to me very
> quickly so I can fix the record in my catalog.  They also notify the publisher
> to publish the correct number in their issues. The NSDP's email address is
> issn@loc.gov
>
> I hope this helps you.
>
> Sincerely,
>
> Barbara Pope, MALS
> Reference/Periodicals Librarian
> Axe Library
> Pittsburg State University
> Pittsburg KS  66762
> bpope@pittstate.edu
> 620-235-4884