Syntax Correction

Hello Gurus,

I am a newbie in BO and working on a requirement. I have the following syntax which works fine if we need range of dates. But I need just one date prompt and not two. How can I fix following syntax which gives me only one prompt for date.

@Select(Details\GMT) >=

CAST( @Prompt('Select Date','D',,Mono,Free)  AS TIMESTAMP(0))

+  CAST ((SELECT HR_DIFF FROM GSC.PERMT_DAYLIGHTS WHERE  @Prompt('Select  Date','D',,Mono,Free) BETWEEN GSC.PERMT_DAYLIGHTS.STRT_TSP AND GSC.PERMT_DAYLIGHTS.END_TSP) AS INTERVAL HOUR)

Regards