Flex sdk in Flash Pro - niggly problem

Gidday

I'm playing around with the AS3XLS lib so I can import Excel files into an AIR app.

I've almost got it working  - only problem is I'm getting compile-time error like...

1046: Type was not found or was not a compile-time constant: DateFormatter.

... for the following classes:

    import mx.formatters.DateFormatter;

    import mx.formatters.NumberBase;

    import mx.formatters.NumberBaseRoundType;
     import mx.formatters.NumberFormatter;

I thought it was related to the flex lib not being installed, but I have the flex swc in my lib path, and use other Flex in the project.

Any idea why the error is appearing?

Cheers!