Propane Tank Test Failed - Red Tagged

After a test of my underground 500 gallon propane tank failed proper cathodic protection it was "red tagged" and could not be refilled. This could be potentially very dangerous if, over time, it were to have rusted and leaked. There were no visible signs of rust anywhere visible. I was allowed to do my own work (since I own my tank) and did the recommended service and replaced the anode bag but a 2nd test still failed. I had to figure out why and fix it in order to pass the safety test and resume propane deliveries.