Maya2015 Standalone License Troubleshooting

Currently holding three standalone license --- which are installed on three workstations as master. 

However, my render slave machines continue to output errors in regards to the license such as 

uninstalling/reinstall maya2015 

update to lastest maya2015 service pack

License file override:

environment variable MAYA_ALT_EN is not set

Maya: License was not obtained

currently license set up under the license.env 

maya_license=unlimited

maya_license_method=standalone. 

I've tried the many possible solutions to resolve this matter via autodesk's suggestion and no results

I also looked for the Ray Server under services and no sight of it just a maya license manager. 

I'm running maya2015 on windows 7. 

I welcome any new way of resolving this matter. if anyone else has encounter this.