Error creating new DWG file using objectARX 2014

[jobinelv]

Hi,
     i am creating app in vs 2012 using .net 4 and autocad version 2014, to export my drawing to DWG format. i have strongly signed objectARX files.
     when i run program i am getting error 'Common Language Runtime detected an invalid program.' 

code snip:

public void DrawLine(Pen pen,double px1,double py1,double px2,double py2)
{
Line line = new Line(new Point3d(px1, py1, 0), new Point3d(px2, py2, 0));
Autodesk.AutoCAD.Colors.EntityColor colent = new Autodesk.AutoCAD.Colors.EntityColor(pen.Color.R, pen.Color.G, pen.Color.B);
line.ColorIndex = colent.ColorIndex; //<<-- exeception here
SaveEntity(line);
}
 
public void SaveEntity(Entity entity)
{
//using (Transaction acTrans = acDB.TransactionManager.StartTransaction()) //<<-- exeception here
Transaction acTrans = acDB.TransactionManager.StartTransaction();
{ // Open the Block table for read 
BlockTable acBlkTbl;
acBlkTbl = acTrans.GetObject(acDB.BlockTableId, OpenMode.ForRead) as BlockTable;
// Open the Block table record Model space for write 
BlockTableRecord acBlkTblRec;
acBlkTblRec = acTrans.GetObject(acBlkTbl[BlockTableRecord.ModelSpace], OpenMode.ForWrite) as BlockTableRecord;
// Create a line that starts at 5,5 and ends at 12,3 
//Line acLine = new Line(new Point3d(5, 5, 0), new Point3d(12, 3, 0));
// Add the new object to the block table record and the transaction 
acBlkTblRec.AppendEntity(entity);
acTrans.AddNewlyCreatedDBObject(entity, true);
// Save the new object to the database 
acTrans.Commit();
}
}