NASA conducted a second fueling test on Friday and everything went fine this time. But the space agency hasn't found why sensors and a valve didn't work properly during the previous test.
"Everything went without a hitch this time, but engineers with the National Aeronautics and Space Administration evaluating the preliminary data were still unsure why the liquid hydrogen sensors gave intermittent readings. The sensors act as fuel gauges that notify the shuttle's main engines to shut down when propellants reach a certain level."
Space shuttle Discovery is now on track for a launch in July. More details at AZCentral