2300MP max display resolution

What is the maximum resolution this projector will diplay?

I have it connected to a laptop and set it to 1280x1024. When I pres the On Screen Display button, it shows Analog RGB 1280x1024/60Hz.

Using my system preferenced I can select 1400x1050 resolution for the projector and the size of the image changes, it becomes smaller, which to me says it is at a new resolution. But when I press the OSD button it still says Analog RGB 1280x1024/60Hz.

If I go to a lower resolution, 800x600 and press the OSD it say Analog RGB 600x600/60Hz.

I used to be able to select 1600x1200 and it would make the image in the projection even smaller, so it seems to be changing resolution.

Why will the OSD show Analog RGB 1280x1024/60Hz even when I have selected a higher resolution?

I am using an intel MacBook.

Thanks