Problem with PSS 747 descent

[gillesdenice 0]

Hello, I fly with the PSS 747 (I know that date a little but to use a FMC in one 747 on FS 2002, I do not have an other alternative), therefore I am cruising at cruising FL in LNAV and VNAV. On the MCP, I indicate (by ex) 10000 feet, first stage of the descent. Arrived at the TOD (Top of Descent), the FMC retards throttle and begins its descent. But there the problem intervenes, the 747 goes down to -5000 fts/mns then goes up with +4000 fts/Mns and thus of following the place to follow a normal descent to -2500/-3000 fts/mns. Thank you with the users current and last for this add-on to let me know if they had this problem and how they solved it. Good flights