Thanks your replying.
Follow your syntax, I received error message:
"An error occurred during local report processing,
An error has occurred during report processing,
Query execution failed for dataset "DataSet1"
ORA-01858: a non-numeric character was found where a numeric was expected"
The parameter type either as datetime or text(string) doesn't make difference.
By the way, I only used one @in front of enddate
What I may missed?