Nintex Webservice calls parent site Workflows when called programatically

Hi,

I have come across a really strange issue with a client.  We created a Site Workflow in a child site.  When we kick off the workflow using a Nintex Webservice call to StartSiteWorkflow it kicks off correctly.  However when we call the same workflow via code it calls the workflows at the parent site and not the chold site, thereby throwing an error that the workflow does not exist.

Has anyone seen this before or have a workaround.  Only workaround I have was to create site workflows on the Parent site, which isn't ideal!

Thanks

Craig