Set the position of the comment by the COM

Right click at the left of the order gantt chart to make a program in which can make or delete a special comment to the order by VB6. (KeyPopupOnOrderGanttChartLeft)
Question
make a comment 4 as test to the order without comment before execute the Add-in of the follow code

Dim pSelOrder As ASBOrder
Set pSelOrder = args.ArgAsObject(kArgOrder)
pSelOrder.Comment(4) = "test"
But the “test” comment is writen into the comment 1.Is the way of writing code is wrong.

Deleting the comment by the COM

There are 4 comments and when try to delete the comment 4,execute the Add-in of the follow code
Dim pSelOrder As ASBOrder
Set pSelOrder = args.ArgAsObject(kArgOrder)
pSelOrder.Comment(4) = “”
The Comment 4 is deleted. However, the whole comments became {comment1;comment2;comment3;} which still has”;” after it.How to delete it