c# - Programmatically create Application Pool, error setting "ManagedPipelineMode" -

i creating application pool iis 6 (windows server 2003r2) programmatically using following code, getting error on line trying set managedpipelinemode

attempt 1

        string metabasepath = @"iis://localhost/w3svc/apppools";          directoryentry apppools = new directoryentry(metabasepath);         directoryentry newpool = apppools.children.add(apppoolname, "iisapplicationpool");         newpool.properties["managedruntimeversion"].value = "v4.0";         newpool.invokeset("managedpipelinemode", new object[] { 0 }); //exception thrown on line         newpool.properties["enable32bitapponwin64"].value = true;         if (!string.isnullorempty(username))         {             newpool.properties["apppoolidentitytype"].value = 3;             newpool.properties["wamusername"].value = username;             newpool.properties["wamuserpass"].value = password;         }         newpool.commitchanges(); 

attempt 2

        string metabasepath = @"iis://localhost/w3svc/apppools";          directoryentry apppools = new directoryentry(metabasepath);         directoryentry newpool = apppools.children.add(apppoolname, "iisapplicationpool");         newpool.properties["managedruntimeversion"].value = "v4.0";         newpool.properties["managedpipelinemode"][0] = 0; //exception thrown on line         newpool.properties["enable32bitapponwin64"].value = true;         if (!string.isnullorempty(username))         {             newpool.properties["apppoolidentitytype"].value = 3;             newpool.properties["wamusername"].value = username;             newpool.properties["wamuserpass"].value = password;         }         newpool.commitchanges(); 

the same exception thrown either way.

exception:

exception hresult: 0x80005006     @ system.directoryservices.interop.unsafenativemethods.iads.putex(int32 lncontrolcode, string bstrname, object vprop)     @ system.directoryservices.propertyvaluecollection.onclearcomplete()     @ system.directoryservices.propertyvaluecollection.set_value(object value) 

turns out issue bit more fundamental thought. first of all, iis 6 doesn't support integrated pipeline mode, switch managedpipelinemode doesn't exist. also, enable32bitapponwin64 doesn't exist in fashion either, turn feature on, command has run (http://extended64.com/blogs/rhoffman/archive/2005/05/10/482.aspx)