AutoCAD Civil 3D :: COGO Creation Fatal Exception?

Here is what I am trying to do,

I am working on an application, where the user would would choose 

Category of point

Sub-category of point

Then click on a Button

1. Which then querry SQLite DB based on the querry a COGO point with relevent RDesc in inserted.

2. A suitable block is inserted in the same location.

3. Updates the handle for the block to the COGO UDP

Now I have commeted the last part of updating UDP.

I have issue inserting COGO.

Sometimes it works some time it throws fatal exception, object instance is not set. I am unable to catch the fatal exception. 

Mini Dump - The thread tried to read from or write to a virtual address for which it does not have the appropriate access

Here is the code,
 
Global.variables.spt_current_COGO_pt = null; PromptPointOptions ppo = new PromptPointOptions("
Select the location to Create a Smart Point : "); PromptPointResult ppr = Global.variables.ed.GetPoint(ppo); if (ppr.Status != PromptStatus.OK) return false;
[Code] .....