\ SweaveInput {} error message missing files that are present

I have a Sweave file, JMP.Rnw, which injects several other files into the same directory. Relevant excerpt from JMP.Rnw (pulling into the prologue):

\SweaveInput{intro.tex} 

      

        
        
        
      

    

And yet, when I run Sweave from the command line, I get an error that the intro.tex could not be found.

> Sweave("JMP.Rnw")
Error in SweaveReadFile(c(ifile, file), syntax, encoding = encoding) : 
 no Sweave file with name ‘./intro.tex ’ found
> 

      

        
        
        
      

    

However, the file definitely exists:

$ find . -name intro.tex
./intro.tex
$ 

      

        
        
        
      

    

This input seems to work for other input files, but I cannot find a pattern that explains why some can be imported and others cannot. There seems to be a number of issues with Sweave and file encoding (see Sweave doesn't seem to have the right to encode .Rnw) , but that doesn't look like a problem here --- all files are us-ascii encoded:

$ file -bi JMP.Rnw
text/x-tex; charset=us-ascii
$ file -bi intro.tex
text/x-tex; charset=us-ascii
$ 

      

        
        
        
      

    

It's really weird that I have a separate Sweave paper setting and just move the intro.tex to that directory and add \ SweaveInput {intro.tex} to that main file works fine (ie builds without any problem). This other article uses a different LaTeX pattern, but this may seem out of place as I understand that Sweave basically ignores all of this until all blocks of code have been identified and executed (although my understanding here could be very wrong).

I am running R version 2.14.2 on an x86_64-pc-linux-gnu (64-bit) machine.

Update . While researching the answer from https://stackoverflow.com/users/210673/aaron , I found that in my additional article where \ SweaveInput {} actually works, the error message generated when trying to invoke a non-existent file does not contain extra space. those.

> Sweave("allocating_visibility.Rnw")
Error in SweaveReadFile(c(ifile, file), syntax, encoding = encoding) : 
 no Sweave file with name ‘./nothere.Rnw’ found
> 

      

        
        
        
      

    

Now I don't know why this trailing whitespace thing happens in one place but not another, but it seems like the most likely cause of the problem.

Update II . So, I think this is still an encoding problem. When I originally created the master.Rnw file, I pasted in some text that was utf-8 encoded. I converted the file back to ascii using http://billposer.org/Software/uni2ascii.html and still got a space error when I ran Sweave. However, when I removed the original \ SweaveInput {} line and retyped it, the problem was gone (ie, it was well-formed and the extra space in the error message was gone).