That's the error message you get when you have some of a scroll/potion/etc in your inventory and also some in your bank or shared bank. It works correctly from your hotbars because you're pointing to that specific stack, but the Icon Bar is using an internal command to cast. The internal command looks for any occurrence of that scroll starting (for unknown reasons) with your bank.
It would be nice if potions/scrolls/etc were checked from inventory first, but that's something only the developers can change. In the meantime, check to make sure the only place you have them is in your character's personal bags.