qr code issues on business cards or other small items?

I have an issue where the simple QR code on my business cards is not being read. I think I know the answer but I would like some clarification so I can make the correct changes.

The square is a little less than 1'X1' my 3G Iphone won't read it, but will read other sizes fine.

Is this too small? Is it my phone's camera?

Also, there is a glittery finish on my cards and I'm thinking the texture isn't helping.

I'm designing my cards myself so I can make adjustments. There is a little bit of wiggle room if I need to make the square a bit larger. I don't want to have to go too large so the square overwhelms the whole card.

Any input will be extremely helpful. I'm going to try and make a jpg I can upload with the shiny finish.