My group recenty had a debate regarding this subject. The question is what happens when the UMD check fails. It doesn't say so we decided it functions normally without the metamagic applied instead of the spell fizzling like a failed concentration check. The debate was regarding a specific situation however. The PC cast his first scroll normally and then attempted to quicken the second one. Obviously the spell can't function normally here if he fails since it would effectively be quickened since he already cast a spell. If we say it simply never happened it feels like a free reroll to me, albeit a round later. The best analogy I could could come up with to adjucate this was the ride skill's quickmount. Basically it that situation one can't even attempt to quickmount unless they have a move action to spend in the event the check fails since it they still mount if they fail. Has anybody had this situation come up and more specifically does anybody have an official references?