You didn't seem to include all the Netsh required components (this is not
about helper dlls).
Check if you got these:
a.. CMD – Windows Command Processor
b.. Network Command Shell
c.. Network Command Shell Interface Context
d.. IP Router Monitor Library
The following are also helpful:
a.. Home Networking Monitory Library
b.. Network Diagnostics
c.. Remote Access Monitory
Please also make sure to resolve all the component dependencies.
More info can be found here:
http://msdn2.microsoft.com/en-us/library/ms838602.aspx