I am having a Checkbox on my vf page and what i want is when i click on my chekbox then only my certain pageblocksection/outpanel should be visible.

i am using following code on vf:

<apex:pageBlockSection title="Select Countries">
<apex:inputCheckbox value="{!reUSA}" label="USA"><apex:actionSupport event="onchange" reRender="USASection" id="Us"/></apex:inputCheckbox>
  </apex:pageBlockSection>

<apex:outputPanel id="USASection" rendered="{!reUSA}"> <apex:inputField value="{!abc__c.myfield__c}" /></apex:outputPanel>

Apex code:

public Boolean reUSA{get; set;}

Now i have used various syntax for rendered attribute like:  rendered="{!IF(reUSA==true,true,false)}"

OR this rendered={!reUSA=true} but the outpanel is not visible when i click on checkbox.

Onething i am confirmed about is when i click on checkbox ,its value is set to true...and i have even tried to display that value  and i get true and onchanging the checkbox ,it shows me false and so on true..false.on further clicking..... but  the thing i didn't understand is if its value sets to true/false..then y is it not able to   substitute its "true/false" value in rendered attribute... in place of {!reUSA}. 

Any suggestion wud be appreciated.. :)