Error "Object reference not set to an instance of an object" in version 1.6.4

I have a program that was running great with DLL version 1.5.15.
I upgraded my DLL to version 1.6.4 and I got an error “Object reference not set to an instance of an object”.
The line of code where the error raises is:
Table.Rows = New Rows

I comented the line and I got the same error in the line:
Pdf.Save("", Savetype.OpenInBrowser, Response)

Dear marcos_peredo,

Thank you for your consideration.

I am sorry for that. But I need more detail to fix the bug. Would you please give me a example code which can reproduce the error?