Random Forest in R: Error in eval(expr, envir, enclos): object not found
In general column names in R need to be formatted without spaces for R to recognize them properly. Importing files with spaces, R will drop in a period and remove the space

This limit is is true for variables as well, but it will not auto-format them for you. 

The most accepted methods for naming are:  

stackOverflow camel case  

stack_overflow with the underscore and a combination of lower and upper as you see fit  

stack.overflow with period (which many dislike because it is often easy to not see the period)

If you use these conventions you will avoid the name issue and be able to focus on the underlying models. 

A caveat, which may or may not matter to you. If you are going to pick a naming style and you work with other languages and pass data around, consider picking a style which works in both or all of them. It is easier for you to have one way, and it makes moving files easier if the names are compatible.