need help...

the getting input form:

<select name="age">     
<option value="25-30">25-30</option>
<option value="31-40">31-40</option>        
<option value="41-50">41-50</option>
<option value="51-60">51-60</option>
</select>

example url

search/?age=25-30

the function php:

if ( $_GET['age'] !="25-30") $age = '("A")'; 
elseif ( $_GET['age'] !="31-40") $age = '("B")'; 
elseif ( $_GET['age'] !="41-50") $age = '("C")'; 
elseif ( $_GET['age'] !="51-60") $age = '("D")'; 
else ( $_GET['age'] !="25-30") $age = '("A")'; 

$search ="http://domain.com/?q='.$age;

the problem: the $age inside $search always returns A (or 25-30) even though i have selected other values (31-40, 41-50, 51-60)

please help..thanks