QScrollBar don't show at the given position which set by setValue()

[wangxy]

i use QVerticalScrollBar in QTableWidget, the QTableWidget constitute of two pages QTableWidgetItem.When i use mouse wheel to turn to the second page successfully, sometimes the QVerticalScrollBar don't show at the given position which set by setValue(). Why ?

Thanks.

[raven-worx]

lets directly skip the guessing phase and post some code pls...