This means that R can't find that specific file on the given location. Double check the location and the precise name of the file (including the extension), have in mind that R is case sensitive.
I have copied as text from file manager. I have even tried file.exists(C:/Homework) and I get "+" as a return result. I apologize, I have about 5 hours of RStudio experience at this point.
In case you haven't noticed, the file has double extension (i.e. .xls.R) this doesn't seem right, you should check on that, if this is an Excel file it should only have a .xls extension.