[Gretl-users] ARMA (1,1)

Good afternoon, Sorry for any inconvenience. I'm trying to forecast the ARMA (1,1) process out of sample (X t+1), but it shows a message that this cannot be done (only in sample fcast). I tried everything, including some commands - fcast, --out-of-sample, dataset addobs 1, --dynamic. I also tried to ad new observations via the graphical interface, to generate forecast, but, without success either. There is something that I'm not doing right. Can anyone please give a thought, what goes wrong? Maybe my commands are inadequate. Tanks in advance, for any valuable help. My best, Fabio ps. I know I can use the coeficients in spreadsheet to generate the fcast, but Im trying to figure out whats is happening.