The error message that you pasted seems to contain a fully qualified classname that contains a space: (between con and fig)
Code:
org.springextensions.actionscript.ioc.factory.con fig.flex.FlexPropertyPlaceholderConfigurer
Could this be just this simple typo? If the class is declared in your application without problems I suspect this to be nothing more than an ordinary typo.
Should you still experience the same problems, could you please post a small sample application that demonstrates the problem? That way we'll be better able to find out what's the problem.
thanks,
Roland