conection php with MySQL (case)

I have problems to make a a case option with my php files.
I have a index.php with links:

Code:

<a href="lib/consultas.php?accion=A">link1</a><br>
<a href="lib/consultas.php?accion=B">link2</a><br>
<a href="lib/consultas.php?accion=C">link3</a><br>
<a href="lib/consultas.php?accion=D">link4</a><br>

And now, I have another php file: consultas.php
In this php i have this code:

Code:

$conexion = mysql_connect("localhost", "user", "pass");
mysql_select_db("jiradb", $conexion);

if($accion!=''){
switch($accion)
{

case 'A':
$queEmp = "select * from membershipbase where user_name like 'gbosch'";
$resEmp = mysql_query($queEmp, $conexion) or die(mysql_error());
$totEmp = mysql_num_rows($resEmp);
echo Usuario: "<strong>".$rowEmp['USER_NAME']."</strong><br>";
echo Grupo: "<strong>".$rowEmp['GROUP_NAME']."</strong><br>";
break;

case 'B':
$queEmp = "select * from membershipbase where user_name like 'jcodina'";
$resEmp = mysql_query($queEmp, $conexion) or die(mysql_error());
$totEmp = mysql_num_rows($resEmp);
echo Usuario: "<strong>".$rowEmp['USER_NAME']."</strong><br>";
echo Grupo: "<strong>".$rowEmp['GROUP_NAME']."</strong><br>";
break;

}
}

When I execute my first link the php i don't work correctly. I don't see nothing! Why???

 

now it's work!!!!!
in the consultas.php:

Code:

$conexion = mysql_connect("localhost", "user", "pass");
mysql_select_db("my_BBDD", $conexion);


if (isset($_GET['accion'])){
switch ($_GET['accion']){

	case 'A':
		...la consulta y la impresión en pantalla...
			}
		}
		break;

	case 'B':
		...la consulta y la impresión en pantalla...
			}
		}
	case 'C':

		...la consulta y la impresión en pantalla...

			}
		}
		break;	
    }
}  

thanks!