getting error in web config - runtime??

     <system.web> Hi,
I want to increase default upload file length size so I added code line below

       <system.web> <httpRuntime maxRequestLength="1048576" executionTimeout="3600" />

already in web config I had this line below which was necessary for another function to work
<httpRuntime requestValidationMode="2.0"/>
       </system.web>
Now I use both I get the error below


TTP Error 500.19 - Internal Server Error The requested page cannot be accessed because the related configuration data for the page is invalid. <div class="content-container">
Detailed Error Information: <div id="details-left"> ...