SSRS Dynamics Date Parameter

Hi,

I have an SSRS report with Dates Parameter. it is compsed of FROMDATE and TODATE. The default value of FROMDATE is the current date and TODATE i added plus 1. This reports will get the transaction for Shift 1 and Shift 2. the shift1 start at 6:00AM of the current date until 6:00PM, then the shift2 will start from 6:00PM of the current date until 6:00AM of the next day.

Here is the code: I set this code in the expression parameter value

FROMDATE :   =DATEADD("d",0,Today)  --the value is 6/11/2014 --current date

TODATE: =DATEADD("d",+1,Today)  --the value is 6/12/2014 --next day

My requirements:

I wanted the date parameter to be dynamics. WHen the time of TODATE falls on 6:00AM, the FROMDATE will change to 6/12/2013 while the TODATE will change to 6/13/2014.

For ex. tomorrow 6/12/2014 6:00AM the value of these two paramter will be change to

FROMDATE: 6/12/2014 

TODATE: 6/13/2014

 Thank you in advance.