multiple select box not showing values

I have a select box that is filled with multiple values and when the user clicks submit, it hightlights all the values in the select box and then sends this to my PHP file. I did a simple: echo ($_POST["imgList"]); to see what was happening and the only value being carried across is the last value selected, even though all values are selected. What might be causing only the last value to be chosen? I was thinking that it was some of the javascript that I use but I recall that it was working just fine with it. I've even tried removing the JS with the same results. Any ideas. thanks