my crop is working fine for first click only then after its showing crop but its sensitivity is very high and taking error image sometimes in my picturebox

if (CropImage == true)
           {
               rect = null;
               picmain.Refresh();
                   rect = new UserRect(new Rectangle( -1,-1,0,0));
               rect.SetPictureBox(picmain);
               CropImage = false;
               cmnucropimg.Hide();
           }

           else
           { rect = null;
                    if (UserRect.Width <= 5)
               {
                   picmain.Refresh();
                   rect = new UserRect(new Rectangle(150, 150, 100, 100));
                   rect.SetPictureBox(picmain);
               }

               CropImage = true;
               //  picmain.Cursor = Cursors.Cross;
           }
         EditImage = false;