Make sure to put it on the smoker as cold as you can get it, Obviously not frozen, but cold.
Smoke can only permeate meat up to about 125 degrees, so the longer it absorbs the smoke the better the smoker ring and bark.
Are you also spraying it during the cooking process?
I typically don't to anything for the first 2 hours, then I spray every half hour to hour and always get some great bark.
I typically smoke between 225 - 250..
Good Luck...
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