XDataWebClient await only available in async procedure

WEB TMS WEB Core
1

procedure TForm1.LoadClients(AFirstName, ALastName: String);
var
Client: TXDataWebClient;
Response: TXDataClientResponse;
begin
try
Client:= TXDataWebClient.Create(nil);
Client.Connection:=Connection;
Response:= TAwait.Exec(XDataWebClient.RawInvokeAsync('IMyService.GetClientsLike',['M', 'T']));
XDataWebDataSet.SetJsonData(Response.Result);
XDataWebDataSet.Open;
finally
FreeAndNil(Client);
end;
end;

//Response:= TAwait.Exec(XDataWebClient.RawInvokeAsync('IMyService.GetClientsLike',['M', 'T']));

//Error: await only available in async procedure

What is the problem?

Response is empty Response:= await(Client.RawInvokeAsync('IMyService.GetClients',[]));
2

Please use the async attribute on the LoadClients method.
More details about this can be found here: