why the if else statement does not run the else statement?

i've got a problem with my if else statement, it does not run the else statement.

here the script.

if ($marital_stat == 'married')
    { 
        if ($age >= 18 || $age < 59)
        { 
            if ($work == 'jobless')
            { 
                if ($place == 'rural')
                { 
                    $loan_credibility == 5;
    }   }   }   }       

    else if ($marital_stat == 'single')
    { 
        if ($age >= 18 || $age < 59)
        { 
            if ($work == 'employee')
            { 
                if ($place == 'rural')
                { 
                    $loan_credibility == 1;
    }   }   }   }       

here the condition that will display output

$A = 'positive';
$B = 'negative';

if ($loan_credibility == 5 ){
    echo $B ;}
else{
    echo $A;
}