System::Call to external .dll during NSIS uninstall

During the installation of my application I install a library used to expor开发者_如何学Ct various functions to $INSTDIR. During uninstallation I want to call a function in this library to perform a task and return. Based on what I've tried so far it seems that the call to the function fails and I always get back 'error' as $0.

This is what I'm running in my uninstallation script:

  SetPluginUnload  alwaysoff
  SetOutPath $INSTDIR
  System::Call "myutils::uninstalling() i.r0"
  DetailPrint 'RETURN CODE: "$0"'
  SetPluginUnload manual

The few examples I've found copied the .dll to a temp directory and then ran System:Call but the library is already in $INSTDIR. Thoughts?

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Wasn't an issue with the NSIS code, the function needed to be exported in the .def file so NSIS could resolve it sans decoration.