-The latest utility for rooting your phone is 1.82 (you can use 1.8 or 1.81 but I recommend you use 1.82)
-Make sure you have selected USB Debugging
-Make sure you are using the USB cable that came with the phone
-Make sure you have NOT selected Mass Storage for type of USB connection
-Make sure you are in AP Fastboot before running the utility
-You may get what appears to be error messages or file not found messages while the utility is running. That is normal. Do not disconnect the phone until you see "exploit failure" or "exploit successful". It take about one full minute for the utility to root the phone...let it run at least that long.
If you have check all the above and your phone still won't root then I'm out of suggestions. Hopefully someone else can figure this out.