data is not fetching when used prompts in derived table

Hi,

I created derived table in the universe and pass the parameter as prompt, I am not able to get the data when i used betwen the dates.

Here "CLOSED_DATE" is in  Unix epoch time and converting to human readable dates.

SELECT * FROM stocks

Where

TO_DATE('01-JAN-1970','dd-mon-yyyy')+((CLOSED_DATE +10800)/60/60/24) between @Prompt('Enter Start Date','D',,,,) and @Prompt('Enter End Date','D',,,,)

Please let me know what's the problem.  We have 4.1 SP6.

For passing string parameter in prompt is working;

-------------------------------------------------

SELECT * FROM stocks

Where SID=@Prompt('Enter ID','C',,,,)

Thanks.

BR