Driveapp jobber

I have a script in a Google Sheet where I'm getting an exception error: Access denied: DriveApp. There is an Archive function were projects in a Master List are updated. However, when I Archive Completed Projects I get an error: Access denied: DriveApp. I need someone to debug the code and/or otherwise tell me how to fix the issue. The particular piece of code is: function archive(){ var spreadsheet = (); var topSheet = ("Active Projects") var archiveSheet = ("Completed Projects"); var archiveCurrRow = ()+1; var topSheetRows = (); //var sheetFolder = findFolder(targetFolderId,targetFolderName) var archiveFolder = findFolder(archivedProjectsFolderId,archiv