Issue uploading macro enabled Excel to Sharepoint(xlsm using xla)

[test]

We have Excel 2007 (xlsm) files which use Addin(xla) ,
On the sharepoint server, we registered them and they open fine when we are
logged on to the sharepoint server.

but, when we uploaded the xlsm file to Sharepoint site (2007)
Issue: None of the users are able to open the xlsm files , Error “Unable
to find the function" this function lives in the Addin..

How to register xla so that xlsm files which use Addin to Sharepoint Site
work?

thanks