Hi Phong,
if the basis work was fine. is any changes were made on this data flow or report recently. as my guess some one changed some functionality which enables that pop like some printer parameter kind.
at RSRT go with debug+ execute and check how that/which function calling that pop screen of DSO edit object.
Please check this link, might be informative.
http://scn.sap.com/thread/1549699
Thanks