A lot of times if find that the required level is placed at the wrong place in a table.
Example (this is an example, there is no scroll with this): In a table for scrolls are 4 levels, and at level 1 is placed that the required level is 40, and at level 2 50, level 3 60, and level 4 is empty.
But in fact, for level 1 no hero level is required, because it's the wizard's tower level that unlocks scrolls. But the here level required for level 2 is 40, so the 1st one was wrong! Probably the right table: Level 1: None. Level 2: 40. Level 3: 50. Level 4:60.
So, mind that if you see level required, it's the level that's required for the NEXT level, and NOT for that level!