Glad you found a solution that works better for you!
For anyone else having this issue:
You can press F9 while playtesting your game to see the values of switches and variables, so you can check if the value of the deposit variable is what it's supposed to be.
The variable for the amount of items being deposited into the bank needs to be stored somewhere that it's not going to be changed until it's withdrawn, so it should be put into its own "Slot 1 Quantity" variable until it needs to be read later when the item is taken back out.
Hope that helps, and I hope it helps you learn more about RPG Maker too! :D