if(empty) validation fires when trying to select 0 from select list

I have a simple select list and just want to make sure that if nothing is selected and it is left on it's default of "Please select", then an error message will display. This works fine but when I select zero then the error still fires. 0 should be an acceptable option.

 

<select class="form-control" name="actual">
	<option value="">Please select</option>
	<option value="0">0</option>
	<option value="1">1</option>
	<option value="2">2</option>
	<option value="3">3</option>
	<option value="4">4</option>
	<option value="5">5</option>
	<option value="6">6</option>
	<option value="7">7</option>
	<option value="8">8</option>
	<option value="9">9</option>
	<option value="10">10</option>
	<option value="11">11</option>
	<option value="12">12</option>
	<option value="13">13</option>
	<option value="14">14</option>
	<option value="15">15</option>
</select>

		if(empty($_POST['actual'])) {
			
			$message .= "Please enter your target <br/>";
		}