php - wrong with $_Files key -

i have big problem, have written code in mobile application upload file server, problem have set dot inside $_files['user.file'];

when invoke $_files['user.file'] upload file, it's seem there no such $_files['user.file'] , think problem because have wrote dot inside key, , server cannot recognize file invalid key

i know it's possible change dot key it's take more time in mobile application.

there way deal problem? such upload files without knowing keys?

any suggestions?

this code, there no files:

<?php    $new_image_name = "yeah.jpg";    move_uploaded_file($_files["user.file"]["tmp_name"], "/var/www/test/".$new_image_name); ?> 

dots in get, post, , cookie variables rewritten underscores:

move_uploaded_file($_files["user_file"]["tmp_name"], "/var/www/test/".$new_image_name);