The "hardkey" command was introduced on the VM700T and therefore is not available on the older VM700A's and VM700's. Instead of using hardkey, you can use a combination of "hardpress" followed by "hardrelease" to achieve the same effect. The hardpress/hardrelease commands have other useful applications such as enabling the Y-C mode (normally done by holding one channel button while pressing another) by executing the following commands: hardpress A hardpress B hardrelease B hardrelease A The above commands would enable the Y-C mode on channels A and B.