Uber

I tried to use Uber for the first time this morning for a pickup in Machelen, but all I kept getting on the app was "No uberPOP Available" Does this just mean Uber doesn't server the area where I was, or just that there was no car close enough at that moment?

I couldn't really find much online about the exact areas of Brussels Uber covers, and there also seems to be hardly any info online about what No uberPOP Available means exactly...

Thanks,
Tim