There are a couple of examples in this post that might be helpful.
However, in the meantime, I took a quick peak at your strategy, in particular the chart called TestRX. Looks like you're checking for errors on the variable called SerialPortAStatus. Besides checking to see if this value is 0 or not, it could also contain helpful info about what's going wrong. (Might want to set a breakpoint before it gets overwritten by the Close which should always work and therefore will wipe out that info in SerialPortAStatus by replacing it with 0.)
Also, if you "inspect" your comm handle and maximize that variable, you can see if it's "Open" and if any characters are coming in on it. Do you know what I mean?
Our product support group might be able to help you too...