Softimage Xsi: Image output resolution in XSI EXP

I have just installed the XSI 3.0 EXP yesterday and, though it seems to work all right, I have run into an annoying problem. This app is supposed to let you save renders up to 510 x 510 px, but I'm not able to render anything different of 400 x 300. Maintain picture ratio is unchecked so I don't know what I'm doing bad. I play with the sliders and the numeric input but they return to their original values:


Picture Ratio: 1,333

Resolution X: 400

Resolution Y: 300

Pixel aspect: 1


Maybe I'm missing something?


See ya


TrueOG