Within the past month, I downloaded the latest EUII patch and then followed the instructions and downloaded and successfully installed the latest AGCEEP version, never having had an earlier one installed (if you don't count EEP). It runs fine. My Windows based PC uses the XP operating system. I have scanned the posts so far in this thread and don't think this is a repeat.
Summary: Couldn't move an additional force into join a siege already in progress in Venice.
Description: Playing as the Ottoman Empire I was at war with the Order of St. John in the late 1510's and early 1520's. Venice was their ally and I was at war with them as well. I had an army of about 35,000 (mixed infantry and cavalry) besieging the province of Venice. The information was showing it was expected to fall in about 6 months, but the previous time I had successfully besieged Venice it took much longer than expected so I wanted to try hurry the process along somewhat by adding a few more troops and, more importantly, a better leader (the one with the crown, my current monarch) to the besieging forces. He was in an adjacent province, but would not accept an order to move in with about 4,000 cavalry or with a larger force that also included about 10,000 infantry.
Silly Hypothesis: Maybe the tide was in and the approaches were blocked? I tried moving a fleet to the nearest sea zone to make sure that it wasn't treating it like a strait. I also tried ordering the land forces to another province and then to Venice, but neither approach worked.
Result: I just waited it out and Venice enventually fell to the siege, so I proposed peace separately with Venice (getting its last two non-capital provinces), then annexed the Order of St. John, to conclude the war, getting Rhodes. The Order of St. John promptly reappeared in Malta, which was formerly Spanish. I will probably want to conquer Venice one last time, so this is of interest for later in the game, but it is mostly just to report it to you, as I appreciate the work done by all who have contributed.
Why couldn't I move some additional forces into the besieged province? In other sieges (in other provinces) I have have been able to do so.