phpExcel: Can't read certain files

```
What steps will reproduce the problem?
1. Reading excel files of specific type

What is the expected output? What do you see instead?
- Notice: iconv(): Detected an illegal character in input string in
c:\PHPExcel\Classes\PHPExcel\Shared\String.php on line 496
- No Errors

Please provide any additional information below.
- It is programmed to read the name of the excel sheets and the data in it.
But for some reasons other excel files doesn't load, returns count of excel
sheet to 0, and sometimes shows this error: Notice: iconv(): Detected an
illegal character in input string in
c:\PHPExcel\Classes\PHPExcel\Shared\String.php on line 496
```

Original issue reported on code.google.com by `jonasivy...@rocketmail.com` on 18 Jun 2013 at 7:49

Attachments:
- [ProblemReference.php](https://storage.googleapis.com/google-code-attachments/php-excel-reader/issue-176/comment-0/ProblemReference.php)

Start with the attached ProblemReference.php and reproduce the failure while reading the affected Excel files. Inspect Classes/PHPExcel/Shared/String.php around line 496, then verify that the sheet count is detected and the iconv notice no longer occurs for the reported files.

Written by the indexing model from the issue text.