SSIS import data access fail when run as a SQL job but runs successfully when the SSIS package is run as such

I have a SQL server agent job.

The second step in this job is Running an SSIS package. This package imports a file from a remote location \\remote\f$\\procedures\imports\sa.txt

The package runs successfully when run when i run it as such using -Right click-> run  package.

However the job fails in the second step with the error : Cannot open the datafile "\\remote\f$\\procedures\imports\sa.txt"

I am sure its has got something to do with the access rights. Can anyone help me understand where i should check for the access permissions??Any other idea why this is failing??

Thanks

Abby