if your script runs a search of subsidiary records (or does a lookup, which is the same thing as a search), employee center roles likely don't have permissions to run searches on subsidiaries. I'm assuming this is a client script, which executes as the current user, so it will be subject to employee center role restrictions. 2 ways around it are: store the information you need in a custom record and allow the employee center roles access to the custom record; or have the client script call a suitelet that can run as admin to do the search.