Grovy ALM HpQC - How to fill ST_ACTUAL design step field : i try to update HpQC result from SOAP-UI groovy script
but i'm currently unable to modify ST_ACTUAL field of design Step,
only to read the current value

for my try, i have 2 steps under a test
Could you help to solve my issue and tell me where i'm wrong 
in advance, thanks a lot for your help and answer


<code>

    //############# Connexion a HpQC ###############
	def tdc = new ActiveXObject ('TDApiOle80.TDConnection')
	tdc.InitConnectionEx(addresse_qc)
	tdc.Login(login_qc, psw_qc)
	tdc.Connect(domain_qc, project_qc)
	log.info "*** connected to QC ***"

    //Catch the testSet campain in the Test Lab
	oTestSetFolder = tdc.TestSetTreeManager.NodeByPath(chemin_dans_qc)
	list_TestSetList = oTestSetFolder.FindTestSets(testSet_name_qc)
	oTestSet = list_TestSetList.Item(1)

    //catch the test list in the Test Lab
	oTestSetFactory = oTestSet.TSTestFactory
	testList = oTestSetFactory.NewList("")
	def nb_test = testList.Count()

    // select first test (item(1) -- Current status test Run - should be  "No Run" 
	selected_test = testList.Item(1) 
	log.info("OnGoing test : " + "ID="+ selected_test.ID +" - "+ selected_test.name + " - status= "+selected_test.Status)

    //  Create a new Test Run and modified final status for try
    OnGoing_RunTest= selected_test.RunFactory.AddItem('Comment 1')
    OnGoing_RunTest.Status = 'Blocked'
    def b=OnGoing_RunTest.ID
    OnGoing_RunTest.Post() 
    OnGoing_RunTest.CopyDesignSteps()
    OnGoing_RunTest.Post() 

  	 Stepslist_of_OnGoing_RunTest = OnGoing_RunTest.StepFactory.NewList("")
 	//def nbsteps= Stepslist_of_OnGoing_RunTest.count()
	def c=1	
	for(designStep in Stepslist_of_OnGoing_RunTest)
	{
		// lecture designStep
		def a=designStep.ID
		// checking previous information : ok
		//log.info("DesignStep_ID="+designStep.ID)
		//log.info("ST_STEP_NAME = "+ designStep.field("ST_STEP_NAME"))
		//log.info("ST_STATUS = "+ designStep.field("ST_STATUS"))
		//log.info("ST_DESCRIPTION = "+ designStep.field("ST_DESCRIPTION"))
		//log.info("ST_EXPECTED = "+ designStep.field("ST_EXPECTED"))

		// updating Status and ST_ACTUAL field
		designStep.Status="Not Completed" // : OK

		// Updating ST_ACTUAL field
		// designStep.Field("ST_ACTUAL")="123" // => KO
		//designStep.item(c).Field("ST_ACTUAL")="123" // ==> KO
		// designStep.item(designStep.ID).Field("ST_ACTUAL")="123" // ==> KO
		// designStep.item(designStep.ID).Field("ST_ACTUAL")="123" // ==> KO
		
		c++	
		log.info("ST_ACTUAL = "+ designStep.field("ST_ACTUAL"))
		designStep.post()
	}

    //Updating Run QC
	selected_test.Post()
	log.info("*** ---- END Test --- ***")
    //#########  déconnection de QC  ############
	tdc.Disconnect()
	//On écrit dans le log
	log.info("### -- QC disconnect -- ### -- END -- ###")

</code>