NANT MSI customaction for Installer.cs methods

[saikris2009]

I have a .net class library which is having Installer.cs that I am trying to configure as a custom action in my build script.

<binaries>
<binary name="EXTDLL" value="${output.dir}LVLTExtensions.dll" />
</binaries>

<customactions>
<customaction action="CA_EXT" type="1" source="EXTDLL" target="Install" />
</customactions>

<sequences>
<sequence type="installexecute" action="CA_EXT" value="-1" condition="Not Installed"/>
</sequences>
I want to call Installer.cs methods on customaction, but when I give target as method name on Installer.cs...I am getting error message on MSI execution{ERROR: DLL required for this install to complete could not be run. Contact your support personnel or package vendor. }

Please help me on this