Qlistview scrollbar invalid on windows

[wushaowen]

Hello all,
I use qlistview to show items of data, when items number reach to some extent,qlistview will add a scrollbar automatically, but using mouse wheel to reach the listview bottom is invalid, the listivew does not scroll at all.By the way,My item is a custom widget,data is stored in the model. Any answer is appreciated!
Attachment is the sample image:

[llev]

On Windows, mouse wheel usually works for focused windows(widgets) only.
Does your listview have focus?