Time Machine using StartCalendarInterval

I want Time Machine (via com.apple.backupd-auto.plist) to use StartCalendarInterval to do weekly backup only. This works on 10.6.8. Having migrated to 10.11.2, I cannot get this modified plist to work. System Log reports: (com.apple.xpc.launchd.domain.system): Could not parse plist: path = /System/Library/LaunchDaemons/com.apple.backupd-auto.plist, error = 109: Invalid property list. (10.6.8 backupd-auto is not the same as this....)

Could an expert please advise on what is wrong with this:

<?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>MachServices</key>

<dict>

<key>com.apple.backupd-helper.status</key>

<dict>

<key>HideUntilCheckIn</key>

<true/>

</dict>

<key>com.apple.backupd-auto</key>

<true/>

</dict>

<key>CFBundleIdentifier</key>

<string>com.apple.backup.launcher</string>

<key>Label</key>

<string>com.apple.backupd-auto</string>

<key>Disabled</key>

<true/>

<key>ProgramArguments</key>

<array>

<string>/System/Library/CoreServices/backupd.bundle/Contents/Resources/backupd- helper</string>

<string>-launchd</string>

</array>

<key>LaunchEvents</key>

<dict>

<key>com.apple.xpc.activity</key>

<dict>

<key>com.apple.backupd-auto</key>

<dict>

<key>StartCalendarInterval</key>

<dict>

<key>Hour</key>

<integer>11</integer>

<key>Minute</key>

<integer>15</integer>

<key>Weekday</key>

<integer>7</integer>

<dict/>

</dict>

</dict>

</dict>

<key>RunAtLoad</key>

<true/>

<key>KeepAlive</key>

<true/>

<key>EnableTransactions</key>

<true/>

<key>POSIXSpawnType</key>

<string>Background</string>

<key>EnablePressuredExit</key>

<true/>

</dict>

</plist>