addProperty('xpath' ...) with String as xpath?

I have following error when I use this code via custom keyword
without using the keyword the script is running fine

Please Suggest
TestCase

CustomKeywords.‘treshhold.SSFTIncludedingGraph.VerifyOptionsIncludedInGraph’()

Error Message
groovy.lang.MissingPropertyException: No such property: myTestObject for class: treshhold.SSFTIncludedingGraph
-------------------------------------Keyword-----------------------------------------------------

package treshhold

import static com.kms.katalon.core.checkpoint.CheckpointFactory.findCheckpoint
import static com.kms.katalon.core.testcase.TestCaseFactory.findTestCase
import static com.kms.katalon.core.testdata.TestDataFactory.findTestData
import static com.kms.katalon.core.testobject.ObjectRepository.findTestObject

import com.kms.katalon.core.annotation.Keyword
import com.kms.katalon.core.checkpoint.Checkpoint
import com.kms.katalon.core.cucumber.keyword.CucumberBuiltinKeywords as CucumberKW
import com.kms.katalon.core.mobile.keyword.MobileBuiltInKeywords as Mobile
import com.kms.katalon.core.model.FailureHandling
import com.kms.katalon.core.testcase.TestCase
import com.kms.katalon.core.testdata.TestData
import com.kms.katalon.core.testobject.TestObject
import com.kms.katalon.core.webservice.keyword.WSBuiltInKeywords as WS
import com.kms.katalon.core.webui.keyword.WebUiBuiltInKeywords as WebUI

import internal.GlobalVariable

public class SSFTIncludedingGraph {


	@Keyword

	public void VerifyOptionsIncludedInGraph(){
		for(int i=1;i<=5;i++){
			String id1="m_sqlRsWebPart_ctl00_ctl19_ctl06_ctl17_divDropDown_ctl0"
			String f="input#"+id1+i.toString()
			String g="//input[@id='m_sqlRsWebPart_ctl00_ctl19_ctl06_ctl15_divDropDown_ctl0"+i.toString()+"']"
			printf g
			myTestObject  = new TestObject("customObject")
			myTestObject.addProperty("xpath", ConditionType.EQUALS,g);
			WebUI.verifyElementChecked(myTestObject, 10)
			WebUI.uncheck(myTestObject)
			selectionStability=new TestObject("ss")
			selectionStability.addProperty("css", ConditionType.EQUALS,"input#m_sqlRsWebPart_ctl00_ctl19_ctl06_ctl15_divDropDown_ctl01")
			WebUI.check(selectionStability)
		}
	}