Each time you call SetKey or FindKey, the method clears any previous values in the Fields property. If you want to repeat a search using previously set fields, or you want to add to the fields used in a search, call EditKey in place of SetKey and FindKey. 

For example, suppose you have already executed a search of the Employee table based on the City field of the "CityIndex" index. Suppose further that "CityIndex" includes both the City and Company fields. To find a record with a specified company name in a specified city, use the following code:

Employee.KeyFieldCount := 2;
Employee.EditKey;
Employee['Company'] := Edit2.Text;
Employee.GotoNearest;

Employee->KeyFieldCount = 2;
Employee->EditKey();
Employee->FieldValues["Company"] = Variant(Edit2->Text);
Employee->GotoNearest();