Under the rules of the simulation, new R&D projects can only begin on January 1, the day that you make decisions for this year. If you started a project last year, and the project is not yet finished, the spreadsheet does not permit any further changes for that product this year.

Tip: Plan your projects to finish in the current year, or if that is not possible, towards the end of the following year. Often you are better off doing a big project in several small steps, each ending in December, rather than one big one. This cuts the product's age in half several times instead of once.