Sorting a multiselect lookup on success

Hi,

Here is a list of options selected in my lookup field called contact type (NB: It is a multiselect) that references my form contact types:

Warehouse

Accounts

Sales

Purchases

I want it to sort to alphabetical order:

Accounts

Purchases

Sales

Warehouse

The code I have written on the On Add-> On Success portion is as follows:

IDList = List();

for each ContactType in input.Contact_Type

{

GetDetails = Contact_Types [ID == ContactType];

IDList.add(GetDetails.ID);

}

GetSortOrder = (Contact_Types[ID in IDList].ID sort by Contact_Type).getall();

input.Contact_Type = GetSortOrder;

For some reason, no matter what I try, this does not work.

Any ideas?

Regards,

Shaheed