Yes you could have the pins in the wrong places. Double check the motherboard drawings. Polarity is not important with switches.
On more thing that you can do is to swap the reset switch with the power switch and use the reset switch to try to boot the system.
We were having this exact problem, and the reset/power switch swap gave us the ability to boot using the reset button. Since my son said he didn't think the reset button was working before and thus never used it, there is no loss, and we are good to go! Thanks jsc!