Pass a series of properties as a string

programming flash
1

I want to pass a series of properties as a string to a webservice:

Version1: This works

 var mxna_ws:WebService = new WebService(WS_URL);
var var1:String = "1";
var var2:String = "2";
var var3:String = "3";
var var4:String = "4";
var categories_pc:PendingCall = mxna_ws[smethod](var1,var2,var3,var4);

Version2:But why doesnt this?..

 var mxna_ws:WebService = new WebService(WS_URL);
var var1:Object = '"1","2","3","4"';
var categories_pc:PendingCall = mxna_ws[smethod](var1);