Alpha cut-out

Hi all. I'm having a problem with a label on a bottle. I created the bottle and made a cylinder just larger in circumference for the label. The cylinder has a narrow break in it. I added a png to a material and applied it to the label. To round the edges, I added alpha and transparency and have tried a combination of both. No matter what I try, the edges of the cylinder are visible outside of the rounded corners of the png. Anyone have any suggestions?
Thanks!

Actually I got a reply from another forum. I hadn't checked Evaluate Transparency in the render settings.
Thanks!