Module addressing has not been configured or is incorrect.
Check the following:
1. Controller (SP_C) Module addressing is correct.
When creating the controller for the first time you will need to register it as a Reader Expander to be able to use it's reader ports. Go to the Configuration tab of the controller and set "Register as Reader Expander" to 1 and the Lock Outputs to the default "Controller PGM 3/4 outputs" setting.
2. Reader Expander Module address.
A new module from the factory will default to an id of 254, this will need to be changed. If you only have the controller and one expander module then the SP-C will be id=1 so make the second expander id=2.
3. Health status.
Check the Health status of your controller to see if anything shows up there.
Update your modules to download changes, review the health status again.