Launchd 無法啟動：“由於某些奇怪的原因無法執行（3）”

Question

我有一個非常簡單的 lanuchd 任務集，用於在每天的特定時間啟動備份腳本。

我可以從命令列完美地運行該命令，沒有任何問題，但是當 lauchd 嘗試啟動它時，會出現以下系統日誌錯誤

9/4/14 9:30:17.534 AM com.apple.launchd.peruser.503[422]: (local.meviocorp.BSbackupScripts[1938]) Job failed to exec(3). Setting up event to tell us when to try again: 2: No such file or directory
9/4/14 9:30:17.534 AM com.apple.launchd.peruser.503[422]: (local.meviocorp.BSbackupScripts[1938]) Job failed to exec(3) for weird reason: 2
9/4/14 9:30:17.535 AM com.apple.launchd.peruser.503[422]: (local.meviocorp.BSbackupScripts) Job should be able to exec(3) now.

plist 是如此簡單，我無法想像這是問題所在：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>local.meviocorp.BSbackupScripts</string>
    <key>ProgramArguments</key>
    <array>
        <string>bs_production_backup.py</string>
        <string></string>
    </array>
    <key>StartCalendarInterval</key>
    <dict>
        <key>Hour</key>
        <integer>9</integer>
        <key>Minute</key>
        <integer>30</integer>
    </dict>
</dict>
</plist>

關於下一步該去哪裡有什麼想法嗎？