IIS URL Rewrite 2.0 - Test condition pattern Error

Hello everybody, I'm new on this forum.

I'm facing a problem with the rewrite module 2.0 on iis 7.5.

The condition on the querystring doesn't seem to work.

The test pattern window can't catch the match and on the site I've got a 404 Error.

1 -  here is the rule in my web.config :

<rulename="Redirect_articles"patternSyntax="ExactMatch"stopProcessing="true">

<matchurl="articles.aspx"/>

<conditionslogicalGrouping="MatchAny"trackAllCaptures="false">

<addinput="{QUERY_STRING}"pattern="id_article=([0-9]+)"/>

</conditions>

<actiontype="Redirect"url="Actualite.aspx?article{C:1}"appendQueryString="false"/>

</rule>

2 - Here is the url I try to catch :

http://mywebsite.be/articles.aspx?id_article=70

3 - when I try with this pattern it work in the "Test patern " window and the page is well redirected

<addinput="{QUERY_STRING}"pattern="id_article=70"/>

4 - But when I test with this :

<addinput="{QUERY_STRING}"pattern="id_article=([0-9]+)"/>

 it doesn't work !

And i got a 404 Error.

Does someone have a response to this ?

Thanks