Is it at least charging the phone?
Make sure you have USB enabled from the Settings>Development>USB Debugging and that "use as disc drive" is selected from the phone drop down bar. Also make sure you are using the USB cable that came with the phone or try a different one... some cables will only charge the phone. Last... make sure you have the drivers for the phone downloaded and installed on the hp mini.... you can try jump starting the installation by rebooting the netbook while the phone is connected... otherwise they will need to be manually installed.