[thelist] Multidimensional Array sort

[The Lists]

Hi,

I am trying to sort multidimensional arrays in PHP. I have been trying 
to use the function 'array_multisort'. :-array_multisort($ar[1], $ar[0], 
ar[2], $ar[3])

If I make the array ($ar) as follows, then it works fine:
Array
(
     [0] => Array
         (
             [0] => EJM10
             [1] => EJM10
             [2] => 23
             [3] => C550
         )

     [1] => Array
         (
             [0] => EJM1
             [1] => EJM1
             [2] => 11
             [3] => A550
         )
     [2] => Array
         (
             [0] => EJM100
             [1] => EJM100
             [2] => 17
             [3] => C560
         )

     [3] => Array
         (
             [0] => EE1
             [1] => EE1
             [2] => 7
             [3] => C650
         )

)

but if I change the 'inner' array from numbers to "words", then it does not:

Array
(
     [0] => Array
         (
             [Callsign] => EJM10
             [Sort] => EJM10
             [ID] => 23
             [Type] => C550
         )

     [1] => Array
         (
             [Callsign] => EJM1
             [Sort] => EJM1
             [ID] => 11
             [Type] => A550
         )

     [2] => Array
         (
             [Callsign] => EJM100
             [Sort] => EJM100
             [ID] => 17
             [Type] => C560
         )

     [3] => Array
         (
             [Callsign] => EE1
             [Sort] => EE1
             [ID] => 7
             [Type] => C650
         )

)

I have tried :-array_multisort($ar[1], $ar[0], ar[2], $ar[3]), but it 
doesn't sort.
I have tried :-array_multisort($ar["Sort"], $ar["Callsign"], ar["ID"], 
$ar["Type"]), but I get the following message:
Warning: Argument 1 to array_multisort() is expected to be an array or a 
sort flag

Any advice would be really appreciated.

BTW, I am trying to sort on the the 'Sort' field and would like a 
Natural sort.

TIA
Alexis