Text entry - use as answer field and as scrap sheet

Dear all,

I'm having a very specific issue with one of the exercises I'm making with Storyline. I am making several math exercises and I want pupils to have the option to note intermediate steps. 

When I use a pick one or drag & drop question type, I can easily add a text entry field, where pupils can make notes and press enter to go to the following line. When they want to submit there answer, they need to press the submit button. These exercises work!

I have also used a text enty question type. There is one text field that gets evaluated, where pupils need to fill in the answer. The other text field does not get evaluated, but can be used to note these intermediate steps. The problem is that, in this specific case, when a pupil presses enter to go to a following line on the scrap sheet, the other text field gets evaluated, and pupils get the message that their answer is wrong, while they haven't even typed one and while I'm not using a 'submit key'.

I have attached an example. Could someone please help me out?

Thanks in advance!

Stephanie