function - PowerShell とグローバル関数

Question

次のコードが機能しないのはなぜですか? この記事によると、global の使用法は正しいはずです: http://technet.microsoft.com/en-us/library/ff730957.aspx

Function global:writeLog {
    param($logType, $logString, $logFile)

    $fileStream = New-Object IO.FileStream $logFile ,'Append','Write','Read'
    $streamWriter = New-Object System.IO.StreamWriter $fileStream

    $time = get-date -Format "hh:mm:ss"
    $streamWriter.writeLine("[${time}][$logType] ${logString}")

    $streamWriter.close()

}

$temp = {
    writeLog -logType "INFO" -logString "Test" -logFile "d:\scripts\powershell\logtest.txt"
}

Start-Job -ScriptBlock $temp 
get-job | receive-job -AutoRemoveJob -Wait

これは、powershell がスローする例外です。

The term 'writeLog' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path was included, 
verify that the path is correct and try again.
    + CategoryInfo          : ObjectNotFound: (writeLog:String) [], CommandNotFoundException
    + FullyQualifiedErrorId : CommandNotFoundException
    + PSComputerName        : localhost