variable not being notice

[divinedesigns1]

hey, im having a problem with making a form into a sticky form, the script works perfectly fine but when i try to make the form into a sticky form its saying the variable is undefine, the form is outside of the script but that shouldnt matter so this is the script im using

if(isset($_POST['submit_contact'])){   // define the variables   $fullname = mysqli_real_escape_string($con, $_POST['fn']);   $company = mysqli_real_escape_string($con, $_POST['cn']);   $email = $_POST['email'];   $sub = mysqli_real_escape_string($con, $_POST['sub']);   $opinion = $_POST['coc'];   // filter the variable   $fullname = strip_tags($fullname);   $fullname = stripslashes($fullname);   $company = strip_tags($company);   $company = stripslashes($company);   $email = strip_tags($email);   $email = stripslashes($email);   $opinion = strip_tags($opinion);   $opinion = stripslashes($opinion);   // define the errors   $errors = array();   // check if the variables are empty   if(empty($fullname) && empty($company) && empty($email) && empty($opinion) && empty($sub)){    echo 'all fields are requested';   }elseif(empty($fullname)){    echo 'Please Enter Your Name';   }elseif(empty($company)){    $cn = 'No Company';   }elseif(empty($email)){    echo 'Please Enter A Valid Email';   }elseif(empty($opinion)){    echo 'Text Is Required';   }elseif(empty($sub)){    echo 'Subject Is Requested';   }elseif(!empty($fullname) && !empty($company) && !empty($email) && !empty($opinion) && !empty($sub)){    // define the receiver    $to = "dds1@dds1.net";    $subject = $sub;    $message = $opinion;    $from = $fullname;    $headers = "From:" . $fullname;    mail($to, $subject, $message, $headers);    echo 'We will response to you as soon as possible';   }  }

as you can see i define the variables making sure everything is in place "ignore the mysqli_real_escape_strings at the top, im just messing around to see what will happen" but this sticky form should be working right?

[niche]

Which variable is it saying is undefined?

[divinedesigns1]

all of them but i got it working tho

[MaranV]

what did you change to get it working then?