https redirect in web.config gives "500" error

Hi.
Without a web.config file in the folder, when I browse to a file in that folder "http://mywebsite.net/gatewaytest.asmx", everything works.  Of course it is not secure (http).  I can also go to "https://mywebsite.net/gatewaytest.asmx" and I am successful (I get a little lock on the browser bar and the SSL cert properties can be displayed)

I want to create a standard-issue "https redirect" in a web.config file, which appears below.  

I copy the web.config file to that folder.  Then, when I browse to "http://mywebsite.net/gatewaytest.asmx", I believe it should re-write the address as "https" and bounce me to "https://mywebsite.net/gatewaytest.asmx", but I get an error:
 500 - Internal server error.
   There is a problem with the resource you are looking for, and it cannot be displayed

So, is there a problem in my web.config file, or do you think there is a problem elsewhere?
Thanks

<?xml version="1.0" encoding="utf-8"?>
<configuration>
    <system.webServer>
        <rewrite>
            <rules>
                <remove name="Redirect to HTTP" />
                <rule name="Redirect to HTTPS" enabled="true" stopProcessing="true">
                    <match url="(.*)" />
                        <conditions>
                            <add input="{HTTPS}" pattern="^OFF$" />
                        </conditions>
                        <action type="Redirect" url="https://{ToLower:{HTTP_HOST}{REQUEST_URI}}" appendQueryString="false" redirectType="Permanent" />
                </rule>
            </rules>
        </rewrite>
    </system.webServer>
</configuration>

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