Moving to the Premiere Elements forum.
Premiere Elements 9.0/9.0.1 restricts that user from importing a still image with greater than 1677216 total pixels.
I have explained the situation in full detail (post 6) in an older thread which dealt with the same issue in Premiere Elements 8.0/8.0.1.
In latest versions of Premiere Elements, that block is removed. But, that does not mean because you can exceed 1677216 total pixels that you should. The classical not to exceed pixel dimensions recommendations that you see online include
for SD project, 1000 x 750 pixels
for HD project, 2200 x 1238 pixels
In later version of Premiere Elements and greater computer resources, these classical recommendations can be stretched to a certain degree.
Any questions or need clarification, please do not hesitate to ask.