dhxCalendar in grid can not show

i use dhtmlx3.6 ,and i use setdateFormat method,the date in the column can show ,but when i change the value ,the new value can save and show ,but if i refresh the page,the value will hidden.i want to know the reason,thank you !

most probably when you save your date on the server its format changes, or some additional symbols appear. For example " " (spaces)