TEXTSCAN requires that you use the command FOPEN:
href = ""<http://www.mathworks.com/help/releases/R2012a/techdoc/ref/fopen.html</a>>
to generate a file identifier for the file to be read. FOPEN syntax is very simple, you can use a single input with the filename (if the file is in current folder or path) or the full path.
If the output is "-1" there may be an error in finding the file, have a look at the path.