two #id's in an if statement for checkboxes

I'm pretty new to Jquery and I have this jquery to check if checkboxes are checked. If not the form should not execute.

It worked fine with only the #validCheck id, but when I added the #feeCheck it doesn't matter witch one is checked, the form executes.

what I want is that the both checkboxes must be checked for the form to execute. If they are both not checked the form should not execute.

  if(!($('#validCheckbox , #feeCheckbox').prop('checked')))
{
  errorMessage += "You must check the checkboxes to continue!<br/>";
  errorCounter++;
  ok = false;
  $("#errorDiv").css({"backgroundColor": "#f9f9f9", "color": "#D2002C", "padding": "10px"});
  $("#errorDiv").html(errorMessage);

}

Do I really have to write two seperate if statements for each checkbox?

I'm reusing the script for multiple forms, some of them have both checkboxes some only have the #validCheck

can someone help me with this.