Right under Diagnostic Status, you see the Diagnostic Buffer. Check that.
The diagnostic buffer is is a very important step with any Siemens PLC, for sure.
Another great tool is to, right click on the PLC and check "receive alarms", then go down to the bottom under the diagnostics tab (properties/info/diagnostics) and click on Alarms.
The diagnostic buffer shows you an event history, but sometimes you need to dig a bit to figure out what is wrong right now. The Alarms tab shows you all the active alarms from the PLC.