Retaining the records from clicking the search button

Question

problem where dropdown list boxes search values are retained from last select even when location dropdown list is not selected. when I am debugging I think the problem is under this code. please give me a solution.

 

#region ShowSearchOptions

private void ShowSearchResults(Boolean visibility)

{

ibShowSearchOptions.Visible = visibility;

btnShowSearchOptions.Visible = visibility;

pnlSearchCriteria.Visible = !visibility;

panSearchResults.Visible = visibility;

if (visibility && this.gvSearchResults.Rows.Count > 0)

this.imgExcelExport.Visible = visibility;

}

#endregion