The structure of report is like
Main table
Row 1 – Another table with master data (sort of header)
Row 2 – Split into two sections : 1st section has 4 columns, second section is a table.
Row 3 – Detail Table
Row 4 – Kinda footer.
Now there are no page breaks anywhere. Somehow after Row 2 in some records there is a page break. The detail table is getting displayed on another page while the 1st two rows are on another page.
The properties pageBreakAtEnd/pageBreakAtStart are false everywhere.
In addition when I set the pageBreakAtEnd for the main table its not working. The next instance of the main table starts from the same page.
Because renderer’s can be very touchy (for good reason), you have to pay careful attention to the overall formatting of any given report. Sometimes page breaks (or even page overflows) appear in the strangest circumstances, a lot of times because the width of the “page” is too large for the format to which you are rendering.
This can also happen in the vertical (which is what I think is happening in your situation?), so you might want to see if one of your row elements could possibly be expressing itself in a way that is much larger than seems when viewing in the designer.
Generally speaking, you should try to keep things as simple, and conservative (with respect to formatting dimensions) as possible. One of the most common problems with page-breaks/overflows, is that something looks fine in the HTML version (through SSRS report manager), but then the slightest boundary encroachment causes the PDF exported version to go all out of whack.
Also, read up closely on what those page break configuration settings are actually doing. The settings in the report designer, can easily cause side effects that cancel out other configurations.