There's not enough info to be able to troubleshoot. What release are you on, do you have any custom settings, are you embedded the view, what screen resolution, and can you attach a packaged workbook so we can try it out here?
workbook is in Tab Desktop 10.2 and the server also in 10.2 version. Size for the dashboard is Automatic. I tried with different range of size but still it is showing white space on the top of the dashboard in the server. I cannot attach the workbook since it is in my company's laptop.
How much whitespace are we talking? Can you at least post a screenshot and just black out the sensitive data?