ScrollPattern.ScrollVertical() for WinForms UserControl do not work correctly

[folkwulf]

Hi to all!
I have a problem: scrolling for UserControl work for first step only, all next steps are ignore.
I do not get any Error in this situation.
How can I fix it?
Thank in advance!

On Application side:

        var aaa = new UserControl();
        aaa.Location = new Point(200, 0);
        aaa.Name = "BedSideReview";
        aaa.Size = new Size(400, 400);
        aaa.AutoScroll = true;
        this.tabPage1.Controls.Add(aaa);

        var bbb = new DataGridView();
        bbb.MinimumSize = new Size(400, 400);
        bbb.Size = new Size(400, 400);
        aaa.Controls.Add(bbb);

        var ccc = new DataGridView();
        ccc.Location = new Point(0, 400);
        ccc.MinimumSize = new Size(400, 400);
        ccc.Size = new Size(400, 400);
        aaa.Controls.Add(ccc);

On Automation side:

        var scrollPattern = GetPattern<ScrollPattern>(uiControl.GetCurrentPattern(ScrollPattern.Pattern));
        scrollPattern.ScrollVertical(ScrollAmount.SmallIncrement);