List files of backup is empty

Hello, I have a problem about list backup files. I have an infra in multi-servers, I see correctly my backups servers, clients and backup. But when I click on 1 backup, the page is empty.

I have look the code, and the function get_tree and I execute command directly on backup server (burp-ui agent) it works:

c:server:b:224:p:/home/
{
    "clients": [
        {
            "name": "cloud.socodex.eu",
            "run_status": "running",
            "protocol": 1,
            "phase": "unknown",
            "backups": [
                {
                    "number": 224,
                    "timestamp": 1466953164,
                    "flags": [
                        "manifest"
                    ],
                    "logs": {
                        "list": [
                            "backup",
                            "backup_stats"
                        ]
                    },
                    "browse": {
                        "directory": "/home",
                        "entries": [
                            {
                                "name": ".",
                                "dev": 65026,
                                "ino": 2,
                                "mode": 16877,
                                "nlink": 7,
                                "uid": 0,
                                "gid": 0,
                                "rdev": 0,
                                "size": 4096,
                                "blksize": 4096,
                                "blocks": 8,
                                "atime": 1466870403,
                                "ctime": 1463510688,
                                "mtime": 1463510688
                            },
                 [...]
                        ]
                    }
                }
            ]
        }
    ]

I have looking for ACL, but I have no errors 403. I try to launch script with -d mode but I see no log:

burp-ui -c burp-ui.cfg -d -v -l /tmp/logs.log

In backup server, burp version is burp-2.0.40. and burp-ui: v0.2.1

Regards, Ben