You're attempting to use a format that is not supported by your ReportViewer. Have a look at:
Report.Render Method (String) (Microsoft.Reporting.WinForms)[
^]
This could be from 1 of 2 things:
1. You have a LocalReport extension installed to render HTML, and the space in the string is messing things up and you can render "HTML4.0", but not "HTML 4.0".
2. According to the documentation the reports available in local mode (which is what you're using with LocalReport) do not include HTML. You'll need to use the WebForms namespace and ServerReport class (with an "HTML4.0" namespace) for that.