Hi,
Please check your BW side data, date field having any null values then #,not assigned values coming from BEX Query.
In crystal formatted the date field many ways.
1. Write click on data field -> format field -> date tab -> by default system date assigned -> you can assign what format you want.
2. Write a formula to display the date field: http://www.c-sharpcorner.com/UploadFile/mahesh/DateFormatInCR06132007092248AM/DateFormatInCR.aspx
Thanks,
DJ