PHP form validation error -

hi beginner in programming php , while trying form validation got error:

"fatal error: can't use function return value in write context in c:\xampp\htdocs\web\proiecte\cristina\formular.php on line 67"

this html section:

<form id ="fabrica" action="formular.php" method="post">     <input type="checkbox" name="unu"/> </form> 

and php code:

if(isset($_post('unu'))){                         echo "<tr>";                         echo "<td>a mers</td>";                         echo "</tr>";                     } 

what doing wrong?

_post associative array (a superglobal)

you can access content using regular array syntax

$_post['unu'] 

instead of

$_post('unu')