Just looked your file. The dimension you have as the YearNew is not a date type but rather it is a string type, thus you can't use forecast on this type of viz. Please see troubleshooting help here: Resolving Forecasting Errors
So I created a new field (Date) to use and now I'm able to select the forecast option. However, I get a warning saying that there is no forecast due to missing values. I've double checked my data and I have no missing data...not sure what else to do.
Trend_Forecast Test.twbx 1,023.6 KB
Just looked at your file, you have indeed missing values in the terms of enough number of dates for the purpose of forecasting. Look how many dates you have for this forecast:
As you see, it is very short, so you should have more date otherwise it is too short to compute forecast. See notes below: