can’t upload image

I changed my “WordPress” file to “blog”, when I want to insert an image to a new post, the image can’t be uploaded.

I create a file \blog\wp-content\uploads\2009\11 , but nothing change.

The image is automatically uploaded to the \wordpress\wp-content\uploads\2009\11,but not the \blog\wp-content\uploads\2009\11.

How to modify this problem.

Thanks in advance.