IIS Module: fails with large data element

I have a web service that takes the following as input. Here is the wsdl:

<complexType name="FileAttachmentContents">
<complexContent>
<extension base="ae:FileAttachment">
<sequence>
<element name="checksum" type="xsd:long" minOccurs="1" maxOccurs="1"/>
<element name="encodedContents" type="xsd:base64Binary" minOccurs="1" maxOccurs="1" nillable="false"/>
</sequence>
</extension>
</complexContent>
</complexType>

With the axis2_http_server.exe it works fine with a 163KB file, where the contents of the file are written in base64 into the "encodedContents" element. But when I run the IIS module and run the same client test, I get back an error saying that the "encodedContents" element is NULL.

I tried a 1KB file with the IIS module and that worked great. So there appears to be something limiting the sending of a large element when using the IIS module.