Rollovers don't work

Hi.

I've been creating some rollover buttons with Image Ready to make a navigation bar for my website. I uploaded the webpage I want from Internet Explorer to SmartFTP, but the buttons don't show at all (let alone 'rollover' when you pass the mouse over them). Another non-rollover graphic does appear.

I have uploaded the relevant JPEGs to SmartFTP but they still don't appear on the website for the rollover buttons (all I get are those boxes with the red X).

I am a newbie to all this and would be greatful for any help and for your patience and time. Thank you.