That command takes a hex representation of the command and payload, not text/string like you are doing. There are number of threads on here that show how to do it if you search. It would likely be 700502 though .
70 = config command class
05 = parameter 5
02 = Value of 2.
An easier option may be to use the basic zwave tool. Install it as a driver, switch the device to use that driver, change parameter, change back to original driver.
