You can't load an xml file on these receivers, they are closed source so not the type of receiver to do that on. Using the correct default frequency, symbol rate and QAM for your area but just as importantly setting NIT Search to on will be all the information you need, you will not need to add any new TPs, the NIT part standing for Network Information Table where by as long as you have those other details right it'll pull in all the information it needs regarding frequencies and channel from the network itself...
It could be a few things, it could be your own signal itself, try going direct and cutting out any splitters etc. if they are being use, it could be it is actually there but been picked up under a different name for some strange reason or even that there is an issue with your area itself at the moment, they should have added the new Sports 3 and 4 HD along with a couple more in most places as of yesterday I think, not saying it is this but perhaps possible there is just something going on with these group of channels just now, in which case trying again later might be the easy answer.
Personally I would try deleting all channels (go to the factor default menu and choose delete all channels), then scan again making sure the whole frequency, symbol rate and QAM are correct plus NIT Search is set to on (all very important). Try it now see if it does the trick, if not give it another try a little later/tomorrow just in case of local issues etc.
