Also - I forgot to mention - you must have a parameter named the same as the prefilterparametername attribute. So in your RDL:
<ReportParameter Name="CRM_FilteredQuote"><DataType>String</DataType><DefaultValue><Values><Value>...default fetchxml...</Value></Values></DefaultValue><Prompt>CRM_FilteredQuote</Prompt><Hidden>true</Hidden></ReportParameter>
The easiest way to create custom reports is to start with the Report Wizard in CRM, get as far as you can, then download the RDL and take it from there.
hth