Should have it set to both instead of same id as designer for designer and both.

Join the Network <form action="email_processing.php" method="post">

			<input type="text" name="email" value="[email protected]"/ class="default-value"><br> 
			<input type="radio" name="skill" value="1" id="developer"/><label for="developer" class="dev">I'm a developer</label> 
			<div class="clr"></div> 
			<input type="radio" name="skill" value="2" id="designer"/><label for="designer" class="des"> I'm a designer</label> 
			<div class="clr"></div> 
			<input type="radio" name="skill" value="3" id="designer"/><label for="both" class="des">Both</label> 
			<div class="clr"></div> 
			
			<input class="submit_button" type="submit" value=""> 
			</form>