Several times when I'm handled from Ground to Tower, it works out to be the end of my flight.Tower just doesn't authorize me to do anything, neither to enter to the rwy nor to hold short. All this in spite I followed every instruction Ground gave me, most of the time to hold short in the highspeed taxiway.thks

If not using radio Auto-tune, be sure you are on the right frequency for tower after you have acked the ground instruction to contact tower.Contact tower on the correct frequency when you are ready to go at the hold short point. You must be near the runway and allow for distortion of the pilot's perspective of the hold short point so you are really at it and as close to the runway edge as feasible.If many ai are landing it may be too busy for you to get a response right away and the ai may not be spaced far enough apart to allow landing separation including exiting the runway. In version 4 the runway must be clear of ai to get permission to line-up. Do you hear RC tower talking to the ai? That will insure you are on the correct frequency. If you are manually tuning use the frequency in the preflight Controller page, not those of any chart unless you modify the frequencies in RC.Make sure your FSUIPC is up to date as listed in the topic at the forum head to insure ai position is properly reported to RC. Make sure you have performed an RC scenery build to insure RC has the correct runway information and is reading your position correctly.If ai separation on landing and exiting the runway is a problem, search this forum for comments on AISmooth and FS9Configurator for possible relief.

can you give a couple of specific scenarios...1) ground tells me to contact tower at the departure tower, and this happens....(remember, at large airports, ground will tell you to monitor tower, which means, change the frequency, but no actions is require. as you approach the runway, with other ai in front of you, you will hear tower clear them to position and hold, and clear them for takeoff, until it is your turn, and then you will be told what to do)2) tower switches me to ground at the arrival airport, and this happens.....(you better be off the active, when you switch to ground, or you will be spanked :-))and if you can duplicate the problems, follow the directions at the top of the forum on how to make a log, and send it to me, with the description of what happened (callsigns are helpful too, especially if the problem is before or after tower/ground says something to and ai)jd