You must make sure to complete every field or 
else your bid will not go through, even 
the "comments" field.  (I always just 
write 'thank you' or something in the comments 
field.)  If you bid did not go through, you are 
redirected to a mostly white page with some 
writing at the top.  If this happens, just use 
your browsers back button and correct whatever 
field is still empty.

Hope this helps!