Schedule SSIS Package to run using Sql Server Agent

We successfully created and deployed a SSIS package from Visual Studio to the Integration Services Catalog. We can successfully run the SSIS package manually from the Integration Services Catalog (the SSIS package loads data from an excel spreadsheet to a sql database table). When we schedule the SSIS package (from the Integration Services Catalog) in Sql Server Agent, the package fails to run. The job fails because it cannot authenticate the proxy.