SQL Reporting Services Parameter Definition Error

Another (see also my previous post) error I often run into with SQL Reporting Services:

An error occurred during local report processing.
The definition of the report '/ABC' is invalid.
The report parameter 'X' has a DefaultValue or a ValidValue that depends on the report parameter "Y". Forward dependencies are not valid.

This simply means that in your reportparameters, Y should be declared before X.

How to do this:

1. Go to the Layout tab
2. Select the Report object in the properties window
3. Go to the ReportParameters property and edit
4. Move Y above X using the arrows