Migration from 10 to 10.1

[ChrisLang]

I am relatively new to using the ArcGIS libraries, so forgive me if this is off target.

Apparently the historical approach is to move client installs to the latest ArcGIS, and then the SDE server at a later date.

Hence, at the moment, we've moved our client code base to run against 10.1, connect to a 10.1 Licence Server, but connect to the 10 SDE database.

I've updated the C# code to reference the 10.1 assemblies, compiles ok, however when running I get a COMException "The operation was attempted on an empty geometry" (PointClass).

Should I be able to run as described (client 10.1, Licence Server 10.1, SDE 10)?

Or do I need to migrate code as part of the move from 10 to 10.1?

Thanks

[ChrisLang]

OK.. So I've tracked it down, but not sure why there is an issue..

In the past we have instantiated a PointClass as such

IPoint pTempPoint = new PointClass();

Then we would set the X and Y properties to double.NaN.

When binding to these properties that was fine running against 10. However, running against 10.1 that seems to have broken. Setting X and Y to double.NaN seems to have no effect whatsoever. Is this by design? I can't seem to find any doco on setting X and Y to NaN or null?