Hi
I think it is not a field it is a prompt or parameter. so, while running the report it is asking a date input and it is not showing the calender icon to select a date.
I think the prompt or parameter is not a date type. Right click on the the prompt and edit.. now choose Date as datatype insted of String and save it.
Now it will show the calender icon to select date.
Also you need to filter the report based on this prompt. Go in Report--Record and give the following :
{DAtefield} = {?dateprompt}