We always have had frustrating challenges with this one. Whether in Design view or Lay out view. "Sometimes" it work sometimes not. Using the mouse to drag the width of fields on the sub form. Exit the form and when returning the fields are the wrong size as it was before. Searching the internet I found many who needed help with this. I found the code from someone as in image 1. Image 2 shows the error with that. Someone said that it worked when he created his form and subform with "form wizzard", didn't work for me, if I did everything right.
Ruben sometimes fiddle with freeze field and save it and we almost always come right, but not me today. Do you see something in the error message or teach me the way.