Hi,
Thank you for your interest in Syncfusion PDF.
Top margin is not working properly.
I was able to view the condition which is mentioned here. We have resolve the problem by commenting the all Margin values as 0 statement (PageSettings.Margins.All = 0;). Please do find the sample from the below specified location and let me know if this helps.
http://www.syncfusion.com/support/user/uploads/Sample_3e0c6412.zipRegards,
Suba