How to dynamically assign WSDL url for webservice

Dear Experts,

I am trying to dynamically assign WSDl for webservice using a global variable.
eg:

<s:WebService id="wsAcquisitionAsset" wsdl="{service}">
                  
                  <s:operation name="CompareDates" resultFormat="object" result="CompareDates(event)"/>
                  <s:operation name="GetYearDepCalculatedBoth" resultFormat="object" result="GetYearDepCalculatedBoth(event)"/>      
            </s:WebService>




[Bindable]
public var service:String="http://localhost/AssetManagementWS/Webservice.asmx?wsdl";


variable service is initailized on creation complete but when i run my program it is not showing in my network monitor ( webservice is not called).

If i am Statically assigning value to WSDL then my webservice is called successfully.