Report layout in preview differs from browser, a clue ..

I have developed a report where i have to use data from different datasets, to get these on one report i have to use multiple tablix data regions
(one dataset per tablix). The report must appear as one tablix in stead of multiple. The tablix data regions are placed below each other with the same columns.

And that’s where the layout problems start, I made sure the columns from the tablix data regions have the same width and are aligned by using the alignment grids.
While using preview mode it looks great the columns are aligned perfect, but after publishing the report to the reporting server the layout is all fumbled up. The columns are no longer aligned below each other.

After some extensive debugging and playing around, I found the solution: it appears reporting services renders the preview different from the browser, the solution from my problem was to set the cangrow property of the row to false (the default setting is true).

I understand this is the solution to my specific problem but it can give you a hint to your solution, there are several properties that can alter the layout of your report.