How to make a preliminary panel data fixed effect regression analysis

Question

For my bachelor thesis I am researching the impact that demographic changes have on the economy.

I compiled data from 12 different variables, and made a panel data. You can download it here :Data

Data should look like this:

I want to run some very easy model and see the summary.

fixed_model = plm(GDPpCap_Growth_Rate ~ Old_Dependancy_Ratio + Fertility_Rate, data = Panel_dataset, index = c("Country Name", "Year"), model = "within")

summary(fixed_model)

However this code doesnt work for me, i did download packages such as plm.

The error code:

Error in pdata.frame(data, index) : variable Country Name does not exist (individual index)

Any help is appreciated!