ARR Configuration

Hi all. Due to the exponential growth of the server (Lync, Exchange, Webserver, RDServer ...) and due to retirentmen of TMG 2010 I wanted to configure ARR. Everything what I read and watched looked like it is really easy to configure ARR to route requests to Webserver for the start.

I have webserver 2008R2  with websites (bindings in IIS domain.com, www.domain.com), ARR Server 2012 R2 (no bindings in IIS) I configured ARR Server Farm, added Webserver. After that I NATed on the router to forward all request to ARR Server, and now I am getting internal server 500 error. 

URL Rewrite is :

<globalRules>
<rule name="ARR_WebServer_loadbalance" patternSyntax="ECMAScript" stopProcessing="true">
<match url="*" />
<action type="Rewrite" url="http://WebServer/{R:0}" />
<conditions>
<add input="{HTTP_HOST}" pattern="^(www\.)?domain\.com" />
</conditions>
</rule>
<rule name="ARR_SSLVPN_loadbalance" patternSyntax="ECMAScript" stopProcessing="true">
<match url="*" />
<action type="Rewrite" url="http://SSLVPN/{R:0}" />
<conditions>
<add input="{HTTP_HOST}" pattern="^ssl\.domain\.com" />
</conditions>
</rule>
</globalRules>

<webFarms>
<webFarm name="WebServer" enabled="true">
<server address="192.168.33.50" enabled="true" />
</webFarm>
<webFarm name="SSLVPN" enabled="true">
<server address="192.168.33.1" enabled="true" />
</webFarm>

Do I need to do anything else ? 

Thanks