530i Missfire P0306

What is your question?

I have 2004 530i only 120,000 miles. I just replaced the spark plugs about couple months. Now the check engine light in on and I get the code P0306 Cylinder #6 Misfire, So I swapped the plug and the coil with Cylinder #1 and I still get the same code " Misfire Cylinder #6" what else I should do?