You need a micro sd adapter. What has happened is that prior to the S3 all microsd outputs had 8 pins in them, and since then, they have 11 pins, so the adapter you got is made for an 8 pin microsd output when you have an 11 pin output for your S4. I use this and if you look at the picture, you can see the adapter on the right side, which just goes over the top. For HDMI output, I highly recommend that. I can't get ANYTHING else on it-- none of the other features it's supposed to have-- to work, except the charging, but the HDMI out works beautifully.