Drag and drop 'none' option not triggering correct response
I am having a problem with the 'none' drop target on one slide.
The difference between this and other similar drag and drop slides is this drag and drop has only 1 correct target (the other should remain empty when answered correctly.
I have 7 drag items, 2 of which should be placed in 1 target zone and nothing in the other 'box' to get the correct response. i.e. 5 drag items have 'none' set as their drop target.
The problem is that when the correct 2 are placed in the right box, you can place 1 or all the 'none' drop target items in the other 'wrong' box and it returns a 'correct' response.
It is as if it ignores the 'none' and is only registering the drag items which have an allocated drop zone other than 'none'
Can anyone help me solve this?