Strange behaviors with include files

On the main file I have:

     require_once('a.php');

on a.php I have:

     require_once('b.php');

The problem I seem to be having is that Dreamweaver, while reading the include file from the include_path driectory (how else could it know about other dependencies) is showing a.php as being missing.

That is on the simple scenario

On the more complex scenario, in the b.php, I have:

     require_once('a.php');

In that case, a.php gets listed twice in the related files... Clicking on the first one, I get the [ a.php is not on the local disk. Get ] error, clicking on the second instance displays the containing code.

All required files are coded in the same fashion. Like I said, I was under the understanding that Dreamweaver looks for files under PHP's include_path directory FIRST than under the website_root if it did not find the file.

In this case, it appears that some files do find the the related file in the include_path directory while other s are looking in the website_root. This would account for seeing the file twice in the dependencies but not why or how this can happen.

What really puzzles me is the simple scenario where the file gets read (showing dependencies) but appears to be missing.

Moving my required file solves the problem but I still do not know why this is happening.

Note: The required files in question comes form the PEAR Spreadsheet_Excel_Writer package... If that adds anything to the problem.

TIA