This problem usually arises when we have a sub-report even we place it in the main report with extreme care it adds extra lines. In such a scenario I use stealth Sub-report and use the data from sub-report to main report through shared variables, and use these as main report fields. Its an extra work but since we use the sub-report fields as main report fields and place them properly we can overcome challenge of extra lines in extra sheet.
Senior Consultant and Developer
SAP Crystal Reports