I cant seem to get my Isset to work

Question

so currently I can't seem to get my drop down working with my isset. i'm not too sure what the issue is either, the ECHO $doctor never seems to be shown but the code runs on a browser. This is just a small snipped of the full code (which all works fine so i haven't included it).

Any help would be greatly appreciated.

<p> Pick a doctor</p>
<form action='patientRequest.php' class='form' method='post'>
<select name='Doctors'>
<option value="Curly">curly</option>
<option value="Larry">larry</option>
<option value="Moe">moe</option>
</select>
<input class='submit' type='submit' name='DocSub' value='update' />
</form>
<?php
if (isset($_post['DocSub'])){
$doctor=$_post['Doctors'];
if ($doctor =="Curly"){
    echo $doctor;
}
else if  ($doctor =="Larry"){
    echo $doctor;
}
else if  ($doctor =="Moe"){
    echo $doctor;
}
}
?>