Nikon CP3100 Macro questions

Hi. I have tried using macro but seems to have un-reliable results. For eg.
if I were to take a macro shot of a bank notes, it's o.k. But if I were to
take a macro shots of some flowers, the flowers would come out un-focused
whereas some leaves or someother things in the background would be in-focus.
I had tried to make sure the flowers occupied the main LCD and in the center
and the green AF light was on. Any tricks to get it right?

Another problem would be the AF and macro. Whenever I tried to use zoom-in,
the AF light will not focus. Does it means that macro and zoom are
incompatible?

Thanks in advance.
kong