OCS Can't upload submission files

Dear all,
I’m creating a conference using OCS and I’m testing upload submission file as an author user.
In step 2 while i try to upload a submission file. It’s got nothing. A page load for a short time but the file not appear.

I’m not sure what i’ve done wrong. Please give me any suggestion.
Best regards, Kame

Check your PHP configuration (php.ini) against the size of the file you are trying to upload.

A brief upload time followed by a redisplay of the page as if nothing happened matches what you would see if you were uploading a file larger than PHP’s limits.

Thank you very much for your help.
I try upload a very small size of file and it still not working.

By the way the problem is not only while i try to upload a submission file. But also in file browser page.

It came up with this message

I can upload a custom logo for the conference. But can’t upload any document file.
Help me please.

Best regards, Kame

If this occurs for all uploads, it is probably incorrect file permissions on the files_dir. The web user, usually apache or nobody or www-data, needs to be able to write to certain directories on your install. See the file permissions section in the FAQ.

Thank you very much.The problem is about path files and permission.
I just move a folder from another website and forgot to configure file and permission.

You save my day. Thank you very much.
Best regards, Kame