You are getting GPS data but the quality is not RTK.

Symptoms:

When you open a COM port you clearly see that positional data is being received. However the GPS Info window is displaying a fix other than FixedRealTimeKinematic.

Cause:

1. You are connected to the wrong COM port. This is possible if your tablet has an internal GPS and you are connecting to its port. 
2. Your GPS is not receiving RTK correction packets from its base station. 

Solutions:

1. Check to see that you are connected to the correct serial port.
2. There are many reasons a GPS may not be receiving correction packets from its base station. Check your GPS documentation for solutions.