Try either filling in those empty banner links, or just remove the last 3 of these:
HTML Code:
banner[number++] = "<a href='REDIRECT_URL' target='_blank'><img src='BANNER_URL' border='1'></a>"
banner[number++] = "<a href='REDIRECT_URL' target='_blank'><img src='BANNER_URL' border='1'></a>"
banner[number++] = "<a href='REDIRECT_URL' target='_blank'><img src='BANNER_URL' border='1'></a>"