dynamic where-statement?

hi,

i try to write a dynamic statement. it looks like this:

string[,] searchlist = new string[100,100];
int index = 0;

if (cbbWorkflowState.SelectedItem != null) { searchlist.SetValue(new string[2] { cbbWorkflowState.SelectedItem.ToString(), "Status" }, index); index++; }
if (txtOrderRef.Text != "") { searchlist.SetValue(new string[2] { txtOrderRef.Text, "Reference" }, index); index++; }

this is a array, in every entry is a second array with first entry the search string, with wich i try to filter the database entries and second is the entity property.

after that i try to write a dynamic where-statement:

using (ModelUnitOfWork uow = Service.DatabaseService.CreateUnitOfWork()) {
            string where_list = "";
            int count = 1;
            foreach (string search in searchlist)
            {
                where_list += "tv=>tv."+ search[1] +" == "+ search[0];
                if (searchlist.Length != count)
                {
                    where_list += " && ";
                }

           count++;

           }
          IQueryable<TransportOrder> tempTransports;
          tempTransports = uow.TransportOrders.Where(where_list);

}

gut i get an exception:

the where-method has some invalid arguments.

how can i solve this problem?