I'm new to Nant and am editing a build script.  I need to build the assemblies in my project to AllowPartiallyTrustedCallers, however when I add the attribute to the assemblyinfo builder I get the following error:

'...CommonAssemblyInfo.cs' could not be generated.
    Assembly attribute with type 'AllowPartiallyTrustedCallers' could not be loaded.

Any help is greatly appreciated.

This is the part that creates the assemblyinfo.

<target name="update-common-assemblyinfo">
    <echo message="Generating common AssemblyInfo file..." />
    <!-- ensure src/CommonAssemblyInfo.cs is writable if it already exists -->
    <attrib file="${root.dir}\src\CommonAssemblyInfo.cs" readonly="false" if="${file::exists('${root.dir}\src\CommonAssemblyInfo.cs')}" />
    <!-- generate the source file holding the common assembly-level attributes -->
    <asminfo output="${root.dir}\src\CommonAssemblyInfo.cs" language="CSharp">
      <imports>
        <import namespace="System" />
        <import namespace="System.Security" />
        <import namespace="System.Reflection" />
        <import namespace="System.Runtime.InteropServices" />
      </imports>
      <attributes>
        <attribute type="CLSCompliantAttribute" value="true" />
        <attribute type="ComVisibleAttribute" value="false" />
        <attribute type="AssemblyProductAttribute" value="${product.fullname}" />
        <attribute type="AssemblyCompanyAttribute" value="${product.url}" />
        <attribute type="AssemblyCopyrightAttribute" value="${product.copyright}" />
        <attribute type="AssemblyTrademarkAttribute" value="Apache License, Version 2.0" />
        <attribute type="AssemblyCultureAttribute" value="" />
        <attribute type="AssemblyVersionAttribute" value="${project.version}" />
        <attribute type="AssemblyConfigurationAttribute" value="${project.framework}; ${project.version}; ${project.buildtype}" />
        <attribute type="AllowPartiallyTrustedCallers" value="" />
      </attributes>
    </asminfo>
  </target>