Cannot use `Open` on a filename

I am having trouble with opening a file using vim-shell.

I cannot open the following files: 
- d:\do.do
- d:\log.wiki
- d:\temp.tex
  However, I can open the following: 
- d:\temp.tar
- d:\
- d:\temp.tex
- d:\doc.doc

Am I missing an option for the filetype recognition?Thank you!
