not found php file on server

hey everybody ,today i found some problem on my server
i login in net2ftp and upload my php script on my own domain
it upload on it but when i see this file below error is occur on my domain
i upload a.php on server

a.php
<?php
echo "test";
?>
and i see the a.php link
www.example.com/a.php i found this server error


Server Error

404 - File or directory not found.
The resource you are looking for might have been removed, had its name changed, or is temporarily unavailable.

so, what do i do?
all html file are work on it why it not work for php
Anybody Explain me ,Thanks by minkoko :D

You uploaded to the wrong place or your host doesn't support PHP. Try a phphinfo() or ask your host.

Uh.. Have you tried looking in your file index? Why not try and create the file directly on the server. There might be FTP restrictions on script files, or something.

ok ,now i fix my problem
my web had on one file name web.cofnig

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<system.webServer>
<httpRedirect enabled="false" destination="" exactDestination="false" childOnly="false" httpResponseStatus="Temporary" />
<directoryBrowse enabled="false" />
<defaultDocument enabled="true">
<files>
<clear />
<add value="default.html" />
<add value="default.htm" />
<add value="default.asp" />
<add value="default.aspx" />
<add value="index.htm" />
<add value="index.html" />
<add value="index.cfm" />
<add value="index.asp" />
<add value="index.aspx" />
<add value="index.php" />
<add value="awstats.pl" />
</files>
</defaultDocument>
<handlers>
<add name="CGI Script Map" path="*.cgi" verb="5,GET,HEAD,POST" modules="CgiModule" scriptProcessor="\bin\perl.exe &quot;%s&quot; %s" resourceType="File" />
<add name="Perl Script Map" path="*.pl" verb="5,GET,HEAD,POST" modules="CgiModule" scriptProcessor="\bin\perl.exe &quot;%s&quot; %s" resourceType="File" />
<add name="PHP" path="*.php" verb="*" modules="CgiModule" scriptProcessor="" resourceType="Unspecified" />
</handlers>
</system.webServer>
</configuration>

and i remove this file now working my site but
i found some problem at google
when i search my site on google.com
Site is Under Construction
why it problem?