Column Header is not getting replaced in Apex:repeat tag

Apex Class

public  class competitorEntryController {        
	private String Oppid;
	public oppwrapper parentrec{get;set;}
	public List<oppwrapper> opplist{get;set;}
	public competitorEntryController(Apexpages.standardcontroller controller){
		Oppid=(string)controller.getrecord().get('Id');
		parentrec=new oppwrapper();
		for(Opportunity opp:[select id,name,(select id,name,name__c,Stage__c,NextStep__c from Competitors__r order by name),
							Stagename,nextstep from Opportunity where id=:Oppid]){
		parentrec.opp=opp;
		if(opp.Competitors__r.size()>0){
			List<CompetitorWrapper> temp=new List<CompetitorWrapper> ();
			for(Competitor__c cm:opp.Competitors__r){
					competitorWrapper cw=new competitorWrapper();
					cw.comp=cm;
					temp.add(cw);
			}
			parentrec.complist=temp;
		}
		}
		opplist=new List<oppwrapper> ();
		system.debug('*******parentrec.complist:'+parentrec.complist);
		opplist.add(parentrec);
	}
	public PageReference Submit(){
		//update operation on opportunity and competitor records
		Pagereference pag=new PageReference('/'+Oppid);
		return pag;
	}
	public class oppwrapper{
		public opportunity opp{get;set;}
		public List<CompetitorWrapper> complist{get;set;}
		public oppwrapper(){
				complist=new List<CompetitorWrapper>();
		}
	}
	public class competitorWrapper{
		public Competitor__c comp{get;set;}
	}        
}

Visualforce Page

<apex:page standardController="Opportunity" extensions="competitorEntryController">
<apex:form >
    <apex:pageblock title="Competitor section">
        <apex:pageblockButtons >
            <apex:commandButton value="Save" Action="{!Submit}"/>
        </apex:pageblockButtons>
        <apex:pageBlocksection title="Using pageblocktable on VF page. problem with Column header value display in repeat tag" columns="1">
            <apex:pageblocktable value="{!opplist}" var="op">
            <apex:column headervalue="{!Opportunity.name}">
                <apex:pageblocksection columns="1">
                    <apex:inputField value="{!op.opp.stagename}"/>
                    <apex:inputField value="{!op.opp.nextstep}"/>
                </apex:pageblocksection>
            </apex:column>            
            <apex:repeat value="{!op.complist}" var="cp">
               <apex:column headervalue="{!cp.comp.name}">
                   <apex:pageblocksection columns="1">
                            <apex:inputField value="{!cp.comp.Stage__c}"/>
                            <apex:inputField value="{!cp.comp.NextStep__c}"/>
                        </apex:pageblocksection> 
                </apex:column>
            </apex:repeat>      
        </apex:pageblocktable>
        </apex:pageBlocksection>
    </apex:pageblock>
</apex:form>
</apex:page>