How to hide/show parameter dynamic?

There is a date range parameter in my rdl, the list value is "This Week","This Month", "This Year" and "Custom", when user choose "Custom", then display two parameter "Date From" and "Date To" to select custom date range.

My question, how to show "Date From" and "Date To" when user choose "Custom", and will hide these two parameter when user choose other item.

Thanks

You don't say what kind of element Date To and Date From are, but if they are text boxes with lables, you can change their Visible property from "False" to "True" or vice versa, depending on what the user has selected. I suggest that the default poroperty should be False., then make them Visisble if the user chooses "Custom"|||

Thanks for you reply

But the parameter's visible property cannot support formula, and I cannot get the change event of parameter "Date Range", such as selectedIndexChange

I use SRS2005, the "Date Range" is a dropdownlist, "Date From" and "Date To" may be the text box