chrome does not respect font-family

I have a web-page written in HTML, in which I have a button. All the page respects the font-family: 'PT Sans', sans-serif except my button.

body {
  font-family: 'PT Sans', sans-serif;
  margin: 0px 0px 0px 0px;
}   

Here is the button element inside a table:

<button id="createCampaignButton" class="yellowButton" nowrap>CREATE NEW CAMPAIGN</button>

I also used <style> tag like below, it will change the font color but not the font family.

button {
          font-family: 'PT Sans', sans-serif;
          color: red
       }

I searched here but none of them was working for me.

My style-sheet:

<link href='http://fonts.googleapis.com/css?family=PT+Sans:400,400italic,700,700italic' rel='stylesheet' type='text/css'>

.yellowButton {
border: 0 solid #FFCC00;
width:100%;
/*height: 50px;*/
font-size: 16px; 
font-weight: bold;
background-color: #FFCC00; 
padding: 12px 20px;
box-shadow: 0 2px 2px 0 #C2C2C2;
border-radius: 2px;
outline:none;
}
.yellowButton:active {
  border: 0 solid #FFCC00;
  width:100%;
  /*height: 50px;*/
  font-size: 16px; 
  font-weight: bold;
  background-color: #FFCC00; 
  padding: 12px 20px;
  box-shadow: 0 0 0 0 #C2C2C2;
  border-radius: 2px;
  outline: none;
}