Triggered Send via Smart Capture Form & AMPScript

AMPScript, Code, SFMC/ExactTarget
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
   <head>
      <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
      <title>My Form</title>
   </head>
   <body>
      <form name="myForm" id="myForm" method="POST" action="%%= RequestParameter('PAGEURL') =%%">
         <input type="hidden" name="__successPage" id="__successPage" value="http://pages.mysuccesspage.php" />
         <input type="hidden" name="__errorPage" id="__errorPage" value="http://pages.myerrorpage.php" />
         <input type="hidden" name="__contextName" id="__contextName" value="FormPost" />
         <input type="hidden" name="__executionContext" id="__executionContext" value="Post" />
         <table width="600" border="0" cellspacing="0" cellpadding="5">
            <tr>
               <td width="200">Email Address<span class="requiredColor">*</span></td>
               <td width="400"><input id="EmailAddress" name="EmailAddress" maxlength="128" class="formFields longTextFields required" type="email" value="%%=v(@email)=%%"  /></td>
            </tr>
            <tr>
               <td>First Name<span class="requiredColor">*</span></td>
               <td><input name="FirstName" maxlength="50" id="txtFirstName" class="formFields longTextFields required lettersonly" type="text" value="%%=v(@firstname)=%%" /></td>
            </tr>
            <tr>
               <td>Last Name<span class="requiredColor">*</span></td>
               <td><input name="LastName" maxlength="50" id="txtLastName" class="formFields longTextFields required lettersonly" type="text" value="%%=v(@lastname)=%%" /></td>
            </tr>
            <tr>
               <td></td>
               <td><input name="submitBtn" type="submit" value="SUBMIT"id="submitBtn" /></td>
            </tr>
         </table>
      </form>

<span style="display: none;" id="post_code">
%%[
[name="FormPost";type="POST"]

/* ADD/UPDATE DATA EXTENSION  */
VAR @de, @de_col, @updateOptions, @saveOptions, @de_statusCode, @de_statusMsg, @errorCode

SET @de = CreateObject("DataExtensionObject")
SETObjectProperty(@de, "CustomerKey", "DataExtension")

SET @de_col = CreateObject("APIProperty")
SETObjectProperty(@de_col, "Name", "EmailAddress")
SETObjectProperty(@de_col, "Value", RequestParameter("EmailAddress"))
AddObjectArrayItem(@de, "Keys", @de_col)

IF NOT IsNull(RequestParameter("EmailAddress")) THEN
    SET @de_col = CreateObject("APIProperty")
    SETObjectProperty(@de_col, "Name", "EmailAddress")
    SETObjectProperty(@de_col, "Value", RequestParameter("EmailAddress"))
    AddObjectArrayItem(@de, "Properties", @de_col)
ENDIF

IF NOT IsNull(RequestParameter("FirstName")) THEN
    SET @de_col = CreateObject("APIProperty")
    SETObjectProperty(@de_col, "Name", "FirstName")
    SETObjectProperty(@de_col, "Value", RequestParameter("FirstName"))
    AddObjectArrayItem(@de, "Properties", @de_col)
ENDIF

IF NOT IsNull(RequestParameter("LastName")) THEN
    SET @de_col = CreateObject("APIProperty")
    SETObjectProperty(@de_col, "Name", "LastName")
    SETObjectProperty(@de_col, "Value", RequestParameter("LastName"))
    AddObjectArrayItem(@de, "Properties", @de_col)
ENDIF

SET @de_col = CreateObject("APIProperty")
SETObjectProperty(@de_col, "Name", "FullName")
SETObjectProperty(@de_col, "Value", Concat(RequestParameter("FirstName"), " ", RequestParameter("LastName")))
AddObjectArrayItem(@de, "Properties", @de_col)


/* TRIGGERED SEND */
VAR @ts, @tsDef, @ts_sub, @ts_attr, @tsctr, @ts_subkey, @ts_statusCode, @ts_statusMsg, @errorCode
       
SET @ts = CreateObject("TriggeredSend")
SET @tsDef = CreateObject("TriggeredSendDefinition")
SET @ts_subkey = RequestParameter("EmailAddress")
       
SETObjectProperty(@tsDef, "CustomerKey", "TSDefinition")
SETObjectProperty(@ts, "TriggeredSendDefinition", @tsDef)
         
SET @ts_sub = CreateObject("Subscriber")
SETObjectProperty(@ts_sub, "EmailAddress", RequestParameter("EmailAddress"))
       
IF NOT EMPTY(@ts_subkey) THEN
    SETObjectProperty(@ts_sub, "SubscriberKey", @ts_subkey)
ELSE
    SETObjectProperty(@ts_sub, "SubscriberKey", RequestParameter("EmailAddress"))
ENDIF
         
AddObjectArrayItem(@ts, "Subscribers", @ts_sub)
SET @ts_statusCode = InvokeCreate(@ts, @ts_statusMsg, @errorCode)
       
IF @ts_statusCode != "OK" THEN
    RaiseError(@ts_statusMsg, 0, @ts_statusCode, @errorCode)
ENDIF
       
ENDIF

SET @updateOptions = CreateObject("UpdateOptions")
SET @saveOptions = CreateObject("SaveOption")
SETObjectProperty(@saveOptions, "PropertyName", "DataExtensionObject")
SETObjectProperty(@saveOptions, "SaveAction", "UpdateAdd")
AddObjectArrayItem(@updateOptions, "SaveOptions", @saveOptions)

SET @de_statusCode = InvokeUpdate(@de, @de_statusMsg, @errorCode, @updateOptions)

IF @de_statusCode != "OK" THEN
    RaiseError(@de_statusMsg, 0, @de_statusCode, @errorCode)
ENDIF      
]%%
</span>

   </body>
</html>