sig.getQuality() returns -1

using a E-Series Dev board.
As i want to include the cellular quality and strength in my data, i wanted to use the sig.getQuality() and sig.getStrength(). ( i am using the CellularSignal sig = Cellular.RSSI(); up front to create an instance)
Both return -1.

What does that mean?

Not sure if you already solved this, but I had a similar issue with a Boron. The solution, offered by rickkas7, was to put the declaration in the loop rather than in the program header. That worked for me. Here’s a link to the post Getting 0 and -1 from CellularSignal