no spark

hi folks need your input
car ran fine a week ago and now it will not start. found out that there was no spark to the plugs, and no spark coming out of the coil. i have an msd 6al which i tested and it is throwing a good strong spark. i have a mopar performance distributor in it. could it be the coil or distributor? how do you check a coil? can you check the distributor if i'm sending a strong spark from the msd unit? i have checked all grounds and the coil wire.
thanks
terry

If the coil is being told to fire and isn't then the coil is at fault and the quickest test, for me anyway, is a new one.

Terry