These skins provide two seperate options. I think you ticked the box you see in the screenshot below. It is used when you are displaying your contacts in compact mode.
What you have to do is just selecting the Small in the drop down list you see in the screenshot and then change your contact list mode to detailed mode. To do so, find an upside down arrow image in your contact list, click it and select "Show contacts details". You may need to restart Messenger in order the changes at the skin to take effect.