AutoCad: Getting 'Invalid object array exception' in Late Binding while copying Objects

AutoCad: Getting 'Invalid object array exception' in Late Binding while
copying Objects

I have two drawings, dg1 and dg2. I have defined a block 'b1' in dg1 which
I want to copy in dg2. It works well in Early Binding but giving error
when I try code in late binding. The code in question is:
myfile.CopyObjects(objCollection, m_oActiveDoc.Blocks)
And I get exception: Invalid object array exception while I try to copy a
block in other drawing.
How do I do it in late Binding?
I am using Autocad 2009
Thanks