In SharePoint,  inline code is not allowed.  If you need to add some inline code to an aspx page, there is a setting in the web.config that must be set. 

The following XML is wrapped in the SafeMode node. 

   1: <PageParserPaths>

   2:     <PageParserPath VirtualPath="/pathtopage/*" CompilationMode="Always" AllowServerSideScript="true" />

   3: </PageParserPaths>

Remember to change the VirtualPath attribute to your specific path where inline code is to be expected.  This should be set conservatively to now allow all pages with inline code.