reverse proxy issue? Fails on 15.1.5 works on 15.0.17

[PDSBILL]

Here is the config.web file now running on the proxy server. Also the OnConfig event code in my test app as well.
We still are getting the same error.

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<system.webServer>
<rewrite>
<rules>

<rule name="Rewrite rule for ISAPI Intraweb application" stopProcessing="true">
<match url="^MyApp/(.*)" />
<action type="Rewrite" url="http://10.10.250.38/webppreviewer_test/ppwebreviewer.dll/{R:1}" logRewrittenUrl="true" />
</rule>

<rule name="Rewrite rule1 for SA Intraweb application" stopProcessing="true">
<match url="^Proxy/(.*)" />
<action type="Rewrite" url="http://10.10.250.38/{R:1}" logRewrittenUrl="true" />
</rule>
</rules>
</rewrite>
<httpErrors errorMode="DetailedLocalOnly" />
<security>
<requestFiltering>
<requestLimits maxAllowedContentLength="2147483648" />
</requestFiltering>
</security>
</system.webServer>
</configuration>



procedure TIWServerController.IWServerControllerBaseConfig(Sender: TObject);
begin
Self.RewriteURL := '/MyApp';
end;