private void dgvCovers_CellFormatting(object sender, DataGridViewCellFormattingEventArgs e) { if (e.RowIndex == -1) { return; } if (!bb) { return; } PercentageDataGrid grid = (PercentageDataGrid)sender; DataGridViewCell cell = grid.Rows[e.RowIndex].Cells[e.ColumnIndex]; int TechDecorID = -1; string StoreName = string.Empty; if (grid.Rows[e.RowIndex].Cells["TechStoreID"].Value != DBNull.Value) { TechDecorID = Convert.ToInt32(grid.Rows[e.RowIndex].Cells["TechStoreID"].Value); StoreName = AssignmentsManager.StoreName(TechDecorID); cell.ToolTipText = StoreName; } }