Hi,
I'm having trouble with making a transparent cylinder show as transparent in the rendered view. I have the newest version of Blender, and I've been on all the tutorials on transparency, and the documentation, but I can't find anything about the problem I'm having. In the Material tab of the Properties panel, my cylinder shows as transparent. In the 3D View panel, my cylinder shows as transparent. However, when I render, in the UV/Image Editor panel, my cylinder is opaque. I have ensured Properties>Render>Shading>Ray Tracing was checked, this was what the documentation gave as the only solution.
Thanks,
Fairthorne

Are you rendering in Blender render or Cycles? Also, why are you rendering in the UV/image editor window? Is that what you have set to display your rendered result?

I was rendering in Blender Render, although I get the same result when I render in Cycles. The UV/Image Editor opens when I press F12 to render my image.

If there is only the cylinder, with no background, other objects, lighting, etc. then you may only be seeing the plain default background through the transparent cylinder, so it looks opaque. Try adding an image on a plane behind it, set to emission and see if that shows it as transparent.

My transparent cylinder isn't on its own; to be precise, it's the plastic circle covering the pressure gauge on a fire extinguisher like this one.
What do you mean by "set to emission"? Could this be my problem?

Okay, I've worked out what the problem is (mainly by browsing other posts from a long time ago on this forum). I didn't have "Receive Transparent" ticked in the shadows section of the object directly behind my transparent object.

OK, but that option is only available (or required) if you are using Blender render, so when you said Cycles had the same problem, I wasn't sure what was happening. Glad to hear you fixed it.