Error: This Accessory is NOT Supported by iPhone?

Trying to use a sd reader for the iPhone 5 and it keeps telling me Error: This Accessory is NOT Supported by iPhone and it's an iPhone product?

It's possible you're trying to use the Apple SD reader that's made for the iPad; I don't think it works in iPhones too.

Or maybe you're just using some non-Apple product that's defective?

Help in case of iPhone is impossible