I actually did solve the issue about two hours ago. Christian was right, it was namely a badly constructed Javascript function. However, I was also missing a proper parsing of the XML data I receive from the transaction. Now that both have been implemented I can use the suggestion box. There is still a small bug for me to take care of as the autocomplete works perfectly in Mozilla and not quite as expected in Internet Explorer 8, but this should mainly concern my CSS entries.
Thank you, Christian and Padma for the support!