Why is there a yellow 'Yield sign' icon on the activity in question? Could it be that you have not replaced the component from MyDatabase after editing the commands in the database?

If this is indeed the case, replace the component with updated one from MyDatabase or try exporting as a PackAndGo exe file to find out why the warning is there.

If you've done all this, then consider swapping pins 2 and 3 in one end of your serial cable to check whether you need a straight cable or a crossover cable.