普通窗体引用子窗体控件问题

Procedure Tprint.Button1Click(Sender: TObject);
begin
Fagreement_in.frxDBDataset_agreement.CloseDataSource:=true;
Fagreement_in.frxDBDataset_agreement.OpenDataSource :=false;
case radiogroup1.ItemIndex of
0:begin
Fagreement_in .frxDBDataset_agreement.RangeBegin:=rbFirst;
Fagreement_in.frxDBDataset_agreement.RangeEnd :=reLast;
Fagreement_in.frxDBDataset_agreement.RangeEndCount:=0;
end;
1:begin
Fagreement_in.frxDBDataset_agreement.RangeBegin:=rbCurrent;
Fagreement_in.frxDBDataset_agreement.RangeEnd :=reCurrent;
Fagreement_in.frxDBDataset_agreement.RangeEndCount:=0;
end;
2:begin
Fagreement_in.frxDBDataset_agreement.RangeBegin:=rbCurrent;
Fagreement_in.frxDBDataset_agreement.RangeEnd :=reCount;
Fagreement_in.frxDBDataset_agreement.RangeEndCount:=strtoint

(edit1.text);
end;
3: begin
Fagreement_in.frxDBDataset_agreement.RangeBegin:=rbCurrent;
Fagreement_in.frxDBDataset_agreement.RangeEnd :=reLast;
Fagreement_in.frxDBDataset_agreement.RangeEndCount:=0;
end;
end;

Fagreement_in.frxDBDataset_agreement.CloseDataSource:=false;
Fagreement_in.frxDBDataset_agreement.OpenDataSource :=true;
end


错误提示：

Project jzgl.exe raised exception class EAccessViolation with

message'Access violation at address 0059CF17 in module 'jzgl.exe'.Read

of address 0000003CC'.~~~