cannot upload image,video etc with wp 2.5 RC1

when I upload the image or video,there is a error that mention me “Fatal error: Call to undefined function wp_constrain_dimensions() in /home/.gainful/mbeautyadvice/beautyadvice.mobi/wp-admin/includes/image.php on line 173” and when upload the video that mention “Fatal error: Call to undefined function image_downsize() in /home/.gainful/mbeautyadvice/beautyadvice.mobi/wp-includes/post.php on line 2326”, But when i use wp 2.3.3,there is no such problem. I puzzled the upload function. Could anyone give me a hlep? I think it maybe a bug. other is all right. you could see myblog http://www.beautyadvice.mobi. ps: I do not use ajax and cache plugin.