Permission issue with DTS and ASP

Please, help me. I am calling a DTS Package from an ASP page using stored procedure and xp_cmdshell.
DTS package transfers data from SQL tables to excel files to network shared directory. I am getting a access denied error when the DTS package fails. I used the UNC path for the Excel files within DTS package.
I can run the DTS Package from Enterprise Manager successfully, but cannot run it from the ASP page.

Thanks for any and all help.

SQL Server is somewhat complex as far as understanding the security context packages are running under. I do not claim to be an expert. I can tell you what I did to resolve this same issue.

SQL Server runs under an account, sometimes the system account. SQL Server Agent runs under an account, which may be different. The DTS package is owned by an account, and the scheduled job is owned by an account, et cetera. I simply make all of these the same. We have an account for the application, and we log on, run SQL, and everything else with that account.

For the servers we are writing to, we simply grant access to the account above. Everything works fine that way.

So assume you have an application ABC running on SQL installation 123 - We log on to the server as account ABC_SUPPORT, and we run SQL, SQL Server Agent, and everything else under ABC_SUPPORT. We then grant ABC_SUPPORT access to the network share that we need to write to.