ReportViewer pagination based on Grouping on Rownumber expression

=Int((RowNumber(Nothing)-1)/5)

What is happening on the report is, I am getting only the first record of every group (and not all records in that group). Also on the Toolbar Pager, when the report initially comes, it shows: 1 of 2 ? and then when I click on "Next" button, it shows 2 of 3 ? and so on keeps on increasing like this pattern.

I am very new to reporting, and I don't know from where this Question Mark is coming and why its not showing all the records in the group.

Thanks for any help.

UPDATE [1 Day after posting] :-

I have figured it out now, why its happening, the problem is: There are RowGroups attached to the Report that are not getting deleted. When I click on "Advanced" in the bottom pane of Visual Studio, it shows: Column Groups and Row Groups. In a fresh new report, when I drag a Table, the Row Grops contain less number of Items then are here. I have tried deleting the Group by opening its XML View, but then Visual Studio crashed.

Any body knows how to delete the Group from RowGroups ? This might solve the problem.