What value are you trying to pass in? System time?
You can pass values to CR via formulas; Create an empty formula. Place it on the CR design pane. Populate the formula using code. Specifics of the code will depend on SDK used - CR SDK / CR Application Server .NET SDK.
For CR Application Server .NET SDK see:
KBA - 1909599 - How to set the formula syntax used for a report using the .NET Report Document SDK
For CR SDK see:
KBA - 1214187 - Modifying report formula fields at runtime using the Crystal Reports .NET SDK
- Ludek