Regarding the Unit, Inspect Objects at Checkpoint
https://trailhead.salesforce.com/developer_console/developer_console_checkpoints
 cant add a checkpoint on line no 13.

Can anyone please help?

HI ,I am doing a trailhead on salesforce Lighting this is my code 

<aura:component >
    <aura:attribute name="item"  type="Camping_Item__c"  /> <!-- required="true" type="String"  -->
    <p> The Item is <ui:outputText value ="{!v.item}"></ui:outputText></p>
    <p>Name:
        <ui:outputText value="{!v.item.name}" /> 
    </p>

    <p>Quantity:
        <ui:outputNumber value="{!v.item.Quantity__c}" /> 
    </p>

    <p>Price:
        <ui:outputCurrency value="{!v.item.Price__c}" /> 
    </p>

    <p>Packed?:
        <ui:outputCheckbox value="{!v.item.Packed__c}" /> 
    </p>
    
    <p><ui:button label="Packed!" press="{!c.packItem}"></ui:button>
    </p>
</aura:component>


Now Its required of me to :
Add a button to the campingListItem component that when clicked, marks the item as packed.
1.Add a button labeled "Packed!" that calls the packItem controller function when clicked.
2.The controller action marks the item attribute as packed and disables the button.

I have done with the first point
I'm struggling with the second point.

the controller code looks something like this (which currently isnt working)

({
    packItem : function(component, event, helper) {
        var btn= event.getSource();
        var BtnMessage =btn.get("v.label");  
        component.set("v.item","Packed");          
        btn.disabled=false;
    }
})


each time I have failing the trailhead because of this error message
Challenge Not yet complete... here's what's wrong: 
The campingListItem JavaScript controller isn't setting the 'Packed' value correctly.