It shows up with an "Error" in the UI, on Read/Write/Info. Is it worth trying your code with the level converter rather than the resistor method ?
Is there any debug output on the console if I run your UI within Visual Studio ?
To be honest, I am keen to know what is wrong. If you have time and interest, we can try to debug the issue. Yes, level converter is generally preferable but it doesn't mean that resistors won't work unless you made a mistake in wiring. Try level converter for a change. But what you can also do as a first step is not to use the frontend application, instead, run a terminal app like HyperTerminal, select appropriate serial port to talk to Arduino and set the baudrate to 115200. Then type 'AAAA' and you should see chip info (provided that it can talk to your HM-10 module).