WebElementFacade is not clicking on the element in webpage

Question

i tried to write a Click() function in Serenity-bdd as Common methods to use in the framework. But, the webpage element which i stored it as WebElementFacade to call inside the Click() function as below. it is not identifying the element and clicking. it is throwing error as **"NullpointerException"** .Please help where i went wrong.

Note : if i use the Webelement as Target type it is working fine. But i need element as the WebElementFacade function to check for more conditions. please help to solve

WebElementFacade --> Stored in different (.java) like below,

public class ParabankForm extends PageObject {
    
    
     public WebElementFacade REGISTER_BUTTON = $(By.xpath("//*[text()='Register']"));
}

Function:

/*
 * Function Name : Click()
 * Author: Koushick Sudharsanam
 * Purpose: The Actor is used to click on the Webelement Target in Webpage
 * 
 */
public void Click(Actor act, WebElementFacade target) {
    
        if(target.isDisplayed()||target.isClickable())
        {
         act.attemptsTo(Click.on(target));
        }
        else
        {
            act.wasAbleTo(target.waitUntilClickable());
            
            if(target.isCurrentlyEnabled() && target.isClickable())
            {
                act.attemptsTo(Click.on(target));
            }
        }
}

So in Step-definition i will call like this,

@Then("i click on the RegisterButton")
    public void i_click_on_the_register_button() {
        
        Utiltiesfunction.GetInstance().Click(act, obj.REGISTER_BUTTON);
         
    }

Error:

java.lang.NullPointerException
    at net.serenitybdd.core.pages.WebElementResolverByLocator.resolveForDriver(WebElementResolverByLocator.java:25)
    at net.serenitybdd.core.pages.WebElementFacadeImpl.getResolvedELement(WebElementFacadeImpl.java:234)
    at net.serenitybdd.core.pages.WebElementFacadeImpl.getElement(WebElementFacadeImpl.java:229)
    at net.serenitybdd.core.pages.WebElementFacadeImpl.isDisplayed(WebElementFacadeImpl.java:1351)
    at CucumberRunner.my.commonfunction.Utiltiesfunction.Click(Utiltiesfunction.java:37)
    at CucumberRunner.my.stepdefinitions.Parabankdef.i_click_on_the_register_button(Parabankdef.java:84)