Issue pushing item to the end of a PHP array?

I have the following code...

if ($email_selection == "primary") {

     $default_select = "<option value=''>Select Email</option>";
     $select_1 = "selected";
     $to_array[] = $profile_primary_email;

} elseif ($email_selection == "secondary") {

     $default_select = "<option value=''>Select Email</option>";
     $select_2 = "selected";
     $to_array[] = $profile_primary_email;

} elseif ($email_selection == "both") {

     $default_select = "<option value=''>Select Email</option>";
     $select_3 = "selected";
     $to_array[] = $profile_primary_email . ',' . $profile_secondary_email;

} 

if ($manual_email != "") {

    $to_array[] = $manual_email;

}

$to_array_count = count($to_array);

$to = $to_array["0"];

for ($v = 1; $v < $to_count; $v++) {

    $to = $to . ',' . $to_array[$v];

}
Copy code

The function of this code is to get the value of a select input, and based on the select input's value push an email address to the end of$to_array. Then the script makes a string of each email seperated by a comma which will later be used as the$to in the PHPmail() function.

For some reason, the select field contains any value, the email address contained in$manual_email is not appended to the array. If there is no value to the select field, however,$manual_email is appended to the empty array normally.