new carburetor installed ran once, now wont start

Hi,

I installed a new carb on my Echo SRM225 line trimmer and it started and ran great. I ran t for about 5 minutes or so and then shut if off for a couple of minutes, and now it will not start. I have no idea what is going on. Any help would be greatly appreciated.
Thanks

Check that it has a spark.
If it has a spark try to start it wilh a SMALL squirt of starter fluid down the carb.
If it has no spark, check you have not pinched the cut off wire somewhere when you fitted the carb.