Macro/Wide Angle Attachment issue

So, I recently got a nifty macro attachment for my Canon 50D. It is smaller than I realized. What would I need to fix this? I've seen several thread adaptors but have no idea what size would work. I have a 28-135 mm lens.

Exactly what did you buy? Is it the 500D closeup lens that looks like a thick filter? I believe that's a 77mm. According to Amazon, your 28-135 has 72mm threads so you'd need a 72mm to 77mm step up ring to make it fit.

This is what I bought:

http://www.amazon.com …pus-14-42mm/dp/B0025Z7MAE

I have a friend who also has it and uses it but it turns out they use it with lenses from their Rebel and that works fine.

That thing says it fits an 18-55 lens which has 58mm threads. Its too small for your 28-135 with 72mm threads. That really looks like a cheap gimmick. Wide angle and macro are opposite goals. Even if it fit your lens, I wouldn't expect much from a $21 item.

wouldn't an adaptor ring work for it?

You could get a step down ring to make it fit. But you'd still be sticking a small piece of glass in front of a larger piece of glass. That's not good.