Thanks for the giving reply.
We identified the problem.
We tested the application without corrdinateTransformation of the country shapefile into mercator project (Without using bing layer). Its working fine.
Previously we first loaded bing map and then rendered country shape file on the bing layer,
But bing layer is in mercator projection. So we are converting shape file
"CoordinateTransformation" into mercator with well know text format. We are assuming during conversion there was any problem in the sharpmap.
We need bing layer on the canvas. Please give any idea to fix this problem. Thanks in advance.