I am trying to delete a file and am getting this error message

Warning: unlink(Includes/Modules/News_Manager) [function.unlink]: Is a directory in /home/hvknuamn/public_html/mainbuild/Includes/Modules/Module_Manager/Module_Functions.php on line 35

This directory is the place I am calling the unlink function from, I dont understand why im getting this. Any ideas?

Thanks in advance

p.s the file has correct permissions to delete and im not getting file not found, so it cant be that