delphi 路径问题，请高手指教

procedure (Sender: TObject);
begin

if combobox2.Text='外科' then
begin
combobox3.Items.LoadFromFile('d:\外科主治医生.txt');
end
else if   combobox2.Text='内科' then
begin
combobox3.Items.LoadFromFile('d:\内科主治医生.txt');
end
else if   combobox2.Text='内科' then
begin
combobox3.Items.LoadFromFile('d:\内科主治医生.txt');
end
else if   combobox2.Text='妇产科' then
begin
combobox3.Items.LoadFromFile('d:\妇产科主治医生.txt');
end
else
begin
combobox3.Items.LoadFromFile('d:\五官科主治医生.txt');
end;
end;
我在D盘已经建了这五个txt文件，可系统总提示找不到路径