I believe I understand what you want to do. However your primary reason for using the drop down was for quicker entry. What I was trying to explain to you is that in any version of crysal lower than 2008 you cannot have an
optional parameter. If the parameter is in the report design the user must enter data into it (even if you as the designer ignore what they enter). Therefore your primary design reson for the 2 layered date entry approach, quick data entry, is no longer valid. It makes the entry process more clumsy and time consuming.
If you still choose to do this,
add one parameter
name='Date Type' (or what ever you want)
type = string
List of values=static
In the value column add your 2 desired options of 'Yesterday' and 'Other Dates'
OK
add another param
name= 'Custom Dates' (or whatever)
type =date
in Options mark 'allow range values' as true
your select statment will be
(
{?Date Type} = 'Yesterday' and
datediff('d',(dateadd('h',-6,{@datetimeformula})),currentdate)=1
)
or
(
{?Date Type} = 'Other Dates' and
dateadd('h',-6,{@datetimeformula}) in Minimum({?Custom Dates}) to Maximum({?Custom Dates})
)