Item tracking line not working properly

Hi all,

I have create new process for item transaction,  through that I'm tracking item tracking on sales order and posting

But its track according to the list not what i have select from item tracking lines

Eg assume item name is A

Its has 5 tracking line starting

1

2

3

4

5

If I have select tracking line 4 it will display tracking line 4 is selected but after posting tracking line 1 has disappeared, tracking line 4 still available

Any idea about this...