Unable to mine mithril ore with appropriate skill

[Teaboar 0]

Hello,

My mining skill is currently 201, but when I try to mine mithril ore out of "Ooze Covered Mithril Deposists" in the Shimmering Flats, I don't get any loot. The strange thing is that I can even start mining and I get skill gains in mining, but the loot windows never opens. What could be causing this? On a side note, I was able to mine out of a Ooze Covered Silver Deposit in the same location.