"I have never found the flowchart a very good method of describing event/exception driven programs. Where am I going wrong?"

I don't think you're going wrong anywhere!
Have you ever found any tool which is it ideal for every application? Of course not! I have well over half a dozen hammers - because just one hammer is not sufficient for all hammering applications.
The same applies to flowcharts - some things they're good at, some they aren't.