Can anyone Help me or point me in the right direction here please....

Im a Bard lvl 13 TR, i have a 46 UMD.... Not to shabby....

Im issue here....

I can easily get off scrolls of all types without any idea of fail, success on 1's....

Why when i cast ONLY the Reconstruct scroll do i recieve a Dice percentage roll and not a regular dice?

How with a 130%-150% chance or getting this scroll off do i fail on a percentage?

What am i missing?