OpenCellID API key not working

Created by: andr3jx

Request to http://opencellid.org/cell/getInArea?key=XXXXXXXXXXXXXXXXXXX&BBOX=... returns

<?xml version="1.0" encoding="UTF-8"?>
<rsp stat="fail">
<err info="Your API key must be whitelisted to run this operation. 
This service is free of charge as long as your application contributes to the OpenCellID project. 
Should your application meet this requirement, please contact markus@opencellid.org for the authorization of your API key." code="4"/>
</rsp>

EDIT by @SecUpwN: Removed sensitive API key information.