Job Fails accessing mapped drive

I built a package in SSIS that exports some data in a database and writes it to a flat file. The flat file is written to a mapped drive on another server (shared folder). The package runs without failure in SSIS and when I deploy it on the SQL Server. The problem comes when I try to run the package as a job; it fails. If I change the file location to the local c: drive, the job runs to sucess. The id that starts the SQL Server Agent is a domain id that is included in both the domain admin group and the local admin group. All the job log indicates is that the job failed; no details.

What am I missing?

ThanksFully qualifying the share fixed the problem. Sure would like to understand why.