Need help in FindFirstVolumeMountPoint

[BlueSkyMemory]

$RET = DllCall("Kernel32.dll", "int", "FindFirstVolume", "str", "", "str", 255)
ConsoleWrite($RET[1] & @TAB & DriveGetLabel($RET[1]) & @TAB & DirGetSize($RET[1]) & @CRLF)
ConsoleWrite(_GetVolumeMountPoint($RET[1]))
$RET[1] = $RET[0]
While 1
    $RET = DllCall("Kernel32.dll", "int", "FindNextVolume", "int", $RET[1], "str", "", "str", 255)
    If Not $RET[0] Then ExitLoop
    ConsoleWrite(_GetVolumeMountPoint($RET[2]))
    ConsoleWrite($RET[2] & @TAB & DriveGetLabel($RET[2]) & @CRLF)
WEnd

Func _GetVolumeMountPoint($sGUID)
    Local $sResult = ''
    Local $tTag = DllStructCreate("char lpszVolumeMountPoint[256]")
    $aRet = DllCall("Kernel32.dll", "int", "FindFirstVolumeMountPoint", "str", $sGUID, "str", $tTag, 'int', DllStructGetSize($tTag))
    $sResult &= $aRet[2]
    Return $sResult
    $aRet[1] = $aRet[0]
    While 1
        $aRet = DllCall("Kernel32.dll", "int", "FindNextVolumeMountPoint", "int", $aRet[1], "str", $tTag, 'int', DllStructGetSize($tTag))
        If Not $aRet[0] Then ExitLoop
        $sResult &= $aRet[2]
    WEnd
    Return $sResult
EndFunc   ;==>_GetVolumeMountPoint

This is my code. The function is to get all GUIDs and then get the mountpoint of them. But the result is that it can only get which mountpoint I set to, not the drive letter. Do I misunderstand it? So why it  cannot get the drive letter?

[BlueSkyMemory]

I've found another function -- GetVolumePathNamesForVolumeName and it can detect the drive letter.

Thank you!😊