function showStores(thisform){
  if(validateZip(thisform) == true){
    thisform.submit();
  }
}

function validateZip(thisform){
  returnVal = true;
  found = thisform.zip.value.search(/[^0-9]/);
  if(found != -1){
    alert("Please enter a valid zip code.");
    thisform.productid.focus();
    returnVal = false;
  }
  if(document.keg.zip.value == ""){
    alert("Please enter a valid zip code.");
    returnVal = false;
    thisform.zip.focus();
  }
  return returnVal;
}