I am trying to force an entry to be added to the neighbor table. 

An entry can be added manually using 
ndp -s (desired address) (mac address)

If this is done, entries for (desired address) are created in the ndp and routing tables, which can be inspected and 
verified with ndp -a and route show. When these entries exist, communication with the device (desired address) work.

I am generating an unsolicited neighbor advertisement in an attempt to automatically create the entries in the tables 
and duplicate the behavior that occurs when the ndp -s command is performed manually. I want it to occur automatically 
when the device with (desired address) is available.

Since it is known when it is available, and its ipv6 and mac address are known, I filled in an unsolicited neighbor 
advertisement packet and sent it on its behalf to iopkt.

When this is done,an entry gets created for (desired address) in the neighbor table, but the MAC address is missing. It 
shows (incomplete) instead. Could this mean the packet that was created was not formed correctly? I did verify the 
override flag is set. Can this be achieved with an unsolicited neighbor advertisement message or can this only be 
achieved by responding to a neighbor solicitation request?