image upload issue

Hello,
after success-ful instalation and image load I wanted add new logos, and got such warnings:

Warning: getimagesize() [function.getimagesize]: Filename cannot be empty in /autoinstalator/wordpress3/wp-content/plugins/logo-slider/logo-slider.php on line 128

Warning: unlink() [function.unlink]: No such file or directory in /autoinstalator/wordpress3/wp-content/plugins/logo-slider/logo-slider.php on line 132

I tried many images beacuse thought that the problem but same result.
Any idea what make this problem?

http://wordpress.org/plugins/logo-slider/