Hello, 

I have added inlineEditSupport and a commandButton to my vf page, however when testing my command button I am getting the error: 
 

Attempt to de-reference a null object
Error is in expression '{!saveCS}' in component <apex:commandButton> in page r2m_contracts_out: Class.R2MPipeLineController.saveCS: line 15, column 1

An unexpected error has occurred. Your development organization has been notified.

Here is my controller: 
 

public class R2MPipeLineController{

    public List<Opportunity> listOfLive {get; set;}
    public List<Opportunity> listOfViability {get; set;}
    public List<Opportunity> listOfLaunchPad {get; set;}
    public List<Opportunity> listOfContractSent {get; set;}
    public List<Opportunity> listOfQualified {get; set;}
    public Opportunity Live {get; set;}
    public Opportunity Viability {get; set;}
    public Opportunity LaunchPad {get; set;}
    public Opportunity ContractSent {get; set;}
    public Opportunity Qualified {get; set;}
    
    public PageReference saveCS(){
    UPDATE ContractSent;
    return null;
    }
    
public R2MPipeLineController() {
    listofLive = [Select id, name, CreatedDate, Company_Name__c, Vertical__c, Weeks_Live__c, Days_Since_Last_Modified__c, Contract_SENT__c, NextStep, LeadSource, Probability, Spend_Last_Week__c, Spend_Last_30_Days__c, Owner_Name__c, Revenue_All_Time__c from Opportunity WHERE StageName = 'Live' ORDER BY Weeks_Live__c DESC];
    listOfViability = [Select id, name, CreatedDate, Company_Name__c, Vertical__c, Weeks_Live__c, Days_Since_Last_Modified__c, Contract_SENT__c, NextStep, LeadSource, Probability, Spend_Last_Week__c, Spend_Last_30_Days__c, Owner_Name__c, Revenue_All_Time__c from Opportunity WHERE StageName = 'Viability' ORDER BY Days_Since_Last_Modified__c DESC];
    listOfLaunchPad = [Select id, name, CreatedDate, Company_Name__c, Vertical__c, Weeks_Live__c, Days_Since_Last_Modified__c, Contract_SENT__c, NextStep, LeadSource, Probability, Spend_Last_Week__c, Spend_Last_30_Days__c, Owner_Name__c, Revenue_All_Time__c from Opportunity WHERE StageName = 'Launch Pad' ORDER BY Days_Since_Last_Modified__c DESC];
    listOfContractSent = [Select id, name, CreatedDate, Company_Name__c, Vertical__c, Weeks_Live__c, Days_Since_Last_Modified__c, Contract_SENT__c, NextStep, LeadSource, Probability, Spend_Last_Week__c, Spend_Last_30_Days__c, Owner_Name__c, Revenue_All_Time__c, Contract_Age__c from Opportunity WHERE StageName = 'Contract Sent' ORDER BY Contract_Age__c ASC];
    listOfQualified = [Select id, name, CreatedDate, Company_Name__c, Vertical__c, Weeks_Live__c, Days_Since_Last_Modified__c, Contract_SENT__c, NextStep, LeadSource, Probability, Spend_Last_Week__c, Spend_Last_30_Days__c, Owner_Name__c, Revenue_All_Time__c from Opportunity WHERE StageName = 'Qualified' ORDER BY Probability DESC]; 
}
}

and here is the pageblock that is yielding the error: 
 

<apex:form >
             <apex:pageBlock title="Contracts Out - Todd Deluke" mode="inlineedit">
                         <table cellpadding="5" style="border-collapse: collapse;table-layout:fixed" width="1100" border="1" >
                
                <apex:variable var="count" value="{!0}"/>
                <apex:repeat value="{!listOfContractSent}" var="cs">
                                                                         <tr style="display:{!IF(cs.Owner_Name__c ='Todd DeLuke', 'table-row', 'none')}">
                                  
                           
                             <td width="50">
                             <apex:outputField value="{!cs.Probability}" >
                                     <apex:inlineEditSupport event="ondblclick" showOnEdit="saveButton, cancelButton" />
                                </apex:outputField>
                            </td>
                          
                          
                        </tr>
                                                          </apex:repeat>
            </table>
            <apex:commandButton id="update" action="{!saveCS}" value="Update Opptys" 
        styleclass="updateButton"/> 
            </apex:pageBlock>
            </apex:form>

I am new to this type of functionality - and I can't seem to figure out what is causing the error.  Can anyone help?

Thanks in advance!

John