I don’t know why image is not display, I can help you by team viewer, if you need. It won’t allow user to skip item group field, its mandatory and it pop message appear that, item group required.
I wrote validatewrite method on that field which I want mandatory. but it pop up message only when we go on that field and when I directly click button OK,record gets added to form.
If you want the field mandatory in all places in AX, set it as mandatory at table field level. If you want a validation in that one form only, add it to validateWrite() on the data source (see Methods on a Form Data Source if you want to learn about other useful methods).