I am using the "forecast" package from R to adjust ARIMA models to my data. In the models I use external regressors in the following way:

```
library("forecast")
Modelo<-arima(log(Recupera), order=c(12,1,1), xreg = Colocacion, include.mean=FALSE)
```

To make predictions I use the following instruction:

```
Pronostico<-forecast(Modelo, xreg = Colocacion_Prueba)
```

My problem arises when I want to apply the model to updated data:

```
Nuevo_Pronosostico<-forecast(object=log(Recupera_Actualizado), model=Modelo, xreg=Colocacion_Futura)
```

But I generate an error:

```
Error in stats::arima(x = x, order = order, seasonal = seasonal, xreg = xreg, :
lengths of 'x' and 'xreg' do not match
```

I have proven that in `xreg`

the whole history of the external regressor is included but it does not work for me.

I hope you can help me ...