Could not find schema information for the element 'httpruntime'

I'm trying to increase the execution timeout and file upload limit on my asp.net website but when i try to add

<httpRuntime
    executionTimeout="110"
    maxRequestLength="4096">
  </httpRuntime>

i get the following errors:

Could not find schema information for t开发者_StackOverflowhe element 'httpruntime'.
Could not find schema information for the element 'executionTimeout'.
Could not find schema information for the element 'maxRequestLength'.

According to this msdn library link this is how I'm supposed to do it,so what am I missing here ?

Have you tried:

<location path="YourUploadPage.aspx">
    <system.web>
        <httpRuntime maxRequestLength="{your value here}" 
                     executionTimeout="{your value here}" />
    </system.web>
</location>

means, <httpRuntime> section should be inside <system.web> or <location><system.web> sections.