I have a position custom object and there have related job applications for the position. I need to do a mass update the status field of the selected application. I am expecting a page like this to select the job applications for update



But I dont see the checkbox next to my job applications. 
I have created button with multiselect and gave visualforce page as content.

The following is the visualforce code

<apex:page standardController="Job_Application__c" recordSetVar="applications">
    <apex:sectionHeader title="Mass Update the Status of Job Applications"/>
    <apex:form >
        <apex:pageBlock >
            <apex:pageMessages />
            <apex:pageBlockButtons >
                <apex:commandButton value="Save" action="{!save}"/>
                <apex:commandButton value="Cancel" action="{!cancel}"/>
            </apex:pageBlockButtons>
            <apex:pageBlockSection title="Change" collapsible="false">
                <apex:inputField value="{!Job_Application__c.Status__c}"/>
            </apex:pageBlockSection>
            <apex:pageBlockSection title="Selected Applications" columns="1">
                <apex:pageBlockTable value="{!selected}" var="application">
                    <apex:column value="{!application.name}"/>
                    <apex:column value="{!application.position__r.name}"/>
                    <apex:column headerValue="Candidate Name">
                        <apex:outputText value="{!application.candidate__r.First_Name__c & ' ' & application.candidate__r.Last_Name__c}"/>
                    </apex:column>
                    <apex:column value="{!application.Status__c}"/>                    
                </apex:pageBlockTable>
            </apex:pageBlockSection>
        </apex:pageBlock>
    </apex:form>
</apex:page>

This is what I see when I go to position related list. There is no checkbox to select multiple job applications