Date.Addmonths... Not recognised?? What am I doing wrong?

I am using Power Query (actually for Excel for this instance, but also for Power BI).

I have

• A date column [Forecast Month]
• An integer column [Add Month]

I want to create a calculated column, a second date field, by adding the integer (in months) to the original date column.

Please note: I am in Australia, the dates are formatted dd/mm/yyyy

The formula I have tried is

Date.Addmonths([Forecast Month],[Add Month])

However Power Query is throwing this error code:

Expression.Error: The name 'Date.Addmonths' wasn't recognized.  Make sure it's spelled correctly.

I sourced this formula directly from the "learn about Power Query formulas" link that is inside Power Query formula window... What am I doing wrong?