Production Schedule - Gantt chart (manufacturing)

Hi all,
My navision doesn't support me production schedule though it's vers. 4.00 SP1
I also have searched the forum but nothing help me to remedy my pains.
the first pain is about the statement (in the Use gantt charts for production planning
purposes macromedia flash player that I downloaded from download forum): "production schedule doesn't provide new scheduling functionality",
what does it mean ? does it relate to MPS functionality? for example, if a customer
first request delivery date is 020106 with qty 100 units, then 2days after, he suddenly requests 120 units with the additional days only 3 days for the requested delivery date, what will I use to solve this ? directly changes qty in the sales order,use order promising
CTP functionality and MPS/MRP to generate supply order/new or revised prod. order or use
planning facility to create new prod. order ?, if yes, will the production schedule changes
the due date according to the new prod. order?
the second pain is about the statement in the F1 (navision help) by clicking contents..manufacturing..production order..then click check order progress: The Production Schedule window opens showing all existing production orders (except simulated and finished), in the other hand in the production schedule only shows released production order (production order view), as far as I know I can't post the output of last operation by
using firm planned production order (FPPO).so, what progress will be able to see in the FPPO? #-o #-o :-k

pls let me have the remediations...tks

rgds,
Johnson "Merkava" Alonso