I too have tried to get this working but was unsuccessful.
If you look at the agent version number you can use this to get the number you need to use. As an example the current version is 188.8.131.52 which converts to 6010006 basically you replace the dots with 0's. Though I've found this rule of thumb to be wrong if there is a double digit number at the end, in that instance you need to drop one of the 0's.
I usually have a view that looks for 600* which finds any old agents online and then I update them.
not able to gilter the extended version of agent. 184.108.40.206 - 220.127.116.11