You could always do it the long yet effective way of "Vol" works in the cmd for you then try outputting the display
text for cmd.exe
C:Usersmac> vol > C:vol.txt
This would output the drive id and serial number to C:vol.txt afterwards use the following code.
#Include <File.au3>
Local $File = 'C:Vol.txt'
For $n = 1 To _FileCountLines( $File ) Step + 1
$Line = FileReadLine( $File, $n )
If StringinStr( $Line, 'Volume Serial Number is' ) Then
$Line = StringReplace( $Line, 'Volume Serial Number is', '' )
$Line = StringReplace( $Line, ' ', '' )
$DriveID = $Line
EndIf
Next
The code checks the lines in the file for Volume Serial.... Removes it and all blank whitespaces and leaves the code in the variable $DriveID