[Invalid parameter number: number of bound variables does not match number of tokens]

That was it - thank you so much! 

[Invalid parameter number: number of bound variables does not match number of tokens]

So my sql should be this:

 $sql = "INSERT INTO messages SET "
                . "`user_id`  = :userid,"
                . "`recipient` = :recipient,"
                . "`subject` = :subject,"
                . "`cc_email` = :cc_email,"
                . "`reply` = :reply,"
                . "`location` = :location,"
                . "`stationery` = :stationery,"
                . "`ink_color` = :ink_color,"
                . "`fontchosen` = :fontchosen,"
                . "`message` = :messageInput,"
                . "`attachment` = :attachment,"
                . "`messageDate` = :messageDate";

And I change my params to this:

 $params = array(                 ':user_id' => $userid,                
                                                         ':recipient' => $this->message_vars['recipient'],                
                                                          ':subject' => $this->message_vars['subject'],                
                                                           ':cc_email' => $this->message_vars['cc_email'],                
                                                            ':reply' => $this->message_vars['reply'],                
                                                             ':location' => $this->message_vars['location'],               
                                                               ':stationery' => $this->message_vars['stationery'],                
                                                                 ':ink_color' => $this->message_vars['ink_color'],                
                                                     ':fontchosen' => $this->message_vars['fontchosen'],                 
                                                      ':message' => $this->message_vars['messageInput'],                
                                                       ':attachment' => $this->message_vars['attachment'],                
                                                        ':messageDate' => $date

I've defined date like this:

$date = date('Y-m-d H:i:s');

The $user_id is  a session variable that I've assigned to $user_id - is that ok to go in the sql? 

Even making those changes, I get this error:   Invalid parameter number: parameter was not defined, when executing:

$stmt->execute($params) or die(print_r($stmt->errorInfo(), true));

[Invalid parameter number: number of bound variables does not match number of tokens]

I'm getting the dreaded " Invalid parameter number: number of bound variables does not match number of tokens" error and I've looked at this for days.  Here is what my table looks like:

|  id          | int(4)       | NO   | PRI | NULL    | auto_increment |
| user_id     | int(4)       | NO   |     | NULL    |                |
| recipient   | varchar(30)  | NO   |     | NULL    |                |
| subject     | varchar(25)  | YES  |     | NULL    |                |
| cc_email    | varchar(30)  | YES  |     | NULL    |                |
| reply       | varchar(20)  | YES  |     | NULL    |                |
| location    | varchar(50)  | YES  |     | NULL    |                |
| stationery  | varchar(40)  | YES  |     | NULL    |                |
| ink_color   | varchar(12)  | YES  |     | NULL    |                |
| fontchosen  | varchar(30)  | YES  |     | NULL    |                |
| message     | varchar(500) | NO   |     | NULL    |                |
| attachment  | varchar(40)  | YES  |     | NULL    |                |
| messageDate | datetime     | YES  |     | NULL    |        

Here are my params:

            $params = array(                 
               ':user_id' => $userid,                 
               ':recipient' => $this->message_vars['recipient'],                 
               ':subject' => $this->message_vars['subject'],                 
               ':cc_email' => $this->message_vars['cc_email'],                 
               ':reply' => $this->message_vars['reply'],                 
               ':location' => $this->message_vars['location'],                 
               ':stationery' => $this->message_vars['stationery'],                 
               ':ink_color' => $this->message_vars['ink_color'],                 
               ':fontchosen' => $this->message_vars['fontchosen'],                 
               ':message' => $messageInput,                 
               ':attachment' => $this->message_vars['attachment'],                 
               ':messageDate' => $date             );

Here is my sql:

$sql = "INSERT INTO messages (user_id,recipient, subject, cc_email, reply, location,stationery, ink_color, fontchosen, message,attachment) VALUES( $userid, :recipient, :subject, :cc_email, :reply, :location, :stationery, :ink_color, :fontchosen, $messageInput, :attachment, $date);";

And lastly, here is how I am calling it:
            $dbh = parent::$dbh;             
           $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING);              
           if (empty($dbh))    return false;             
                  $stmt = $dbh->prepare($sql);             
                 $stmt->execute($params) or die(print_r($stmt->errorInfo(), true));              
           if (!$stmt) {    print_r($dbh->errorInfo());              }

I know my userid is valid and and the date is set above (I've echo'd these out to make sure).  Since the id is auto_increment, I do not put that in my sql (though I've tried that too), nor in my params (tried that too).  What am I missing?  I feel certain it is something small, but I have spent days checking commas, semi-colons and spelling.  Can anyone see what I'm doing wrong?