Input string is not in a correct format

I am using the below code to display value of the query into the textbox, but I am getting error as
Input string was not in a correct format. Here is my code:-
private void FillCombo() { txtCurrentCompany.Text = CF.ExecuteScaler("SELECT c1.Company_Name FROM dbo.emp_mst em INNER JOIN dbo.company_mst c1 ON em.Comp_mkey = c1.Mkey " + "AND FA_year = '2008' and em.mkey='937'"); } public string ExecuteScaler(string StrQuery) { DB.EConnection(); cmd = new SqlCommand(StrQuery, DB.conn); cmd.Connection = DB.conn; int val=Convert.ToInt32(cmd.ExecuteScalar()); DB.conn.Close(); string ret = val.ToString(); return ret; }