node.save error "Parameter count mismatch" while trying to save with taxonomy

hi,
i am building an app with c# wpf .net v 3.5
i am using the node.save xmlrpc service to save a new node
it works fine untill i try to include taxonomy values with the input parameters

i get this error "Parameter count mismatch" when i try to use the node.save function with taxonomy

can anyone point out what is wrong!!