Powerview connection error - sharepoint-2010

Question

When I try to create a powerview report from an excel spreadsheet in Sharepoint, I get the following error message.
Please help
An error occurred while loading the model for the item or data source 'http://win-lnj1eq8qsfv:16350/PowerPivotTestSite/PowerPivot Gallery/Sum of Sales Quota.xlsx'. Verify that the connection information is correct and that you have permissions to access the data source.
<detail>
<ErrorCode xmlns="http://www.microsoft.com/sql/reportingservices">rsCannotRetrieveModel</ErrorCode>
<HttpStatus xmlns="http://www.microsoft.com/sql/reportingservices">400</HttpStatus>
<Message xmlns="http://www.microsoft.com/sql/reportingservices">An error occurred while loading the model for the item or data source 'http://win-lnj1eq8qsfv:16350/PowerPivotTestSite/PowerPivot Gallery/Sum of Sales Quota.xlsx'. Verify that the connection information is correct and that you have permissions to access the data source.</Message>
<HelpLink xmlns="http://www.microsoft.com/sql/reportingservices">http://go.microsoft.com/fwlink/?LinkId=20476&EvtSrc=Microsoft.ReportingServices.Diagnostics.Utilities.ErrorStrings&EvtID=rsCannotRetrieveModel&ProdName=Microsoft%20SQL%20Server%20Reporting%20Services&ProdVer=11.0.2100.60</HelpLink>
<ProductName xmlns="http://www.microsoft.com/sql/reportingservices">Microsoft SQL Server Reporting Services</ProductName>
<ProductVersion xmlns="http://www.microsoft.com/sql/reportingservices">11.0.2100.60</ProductVersion>
<ProductLocaleId xmlns="http://www.microsoft.com/sql/reportingservices">127</ProductLocaleId>
<OperatingSystem xmlns="http://www.microsoft.com/sql/reportingservices">OsIndependent</OperatingSystem>
<CountryLocaleId xmlns="http://www.microsoft.com/sql/reportingservices">1033</CountryLocaleId>
<MoreInformation xmlns="http://www.microsoft.com/sql/reportingservices">
<Source>ReportingServicesLibrary</Source>
<Message msrs:ErrorCode="rsCannotRetrieveModel" msrs:HelpLink="http://go.microsoft.com/fwlink/?LinkId=20476&EvtSrc=Microsoft.ReportingServices.Diagnostics.Utilities.ErrorStrings&EvtID=rsCannotRetrieveModel&ProdName=Microsoft%20SQL%20Server%20Reporting%20Services&ProdVer=11.0.2100.60" xmlns:msrs="http://www.microsoft.com/sql/reportingservices">An error occurred while loading the model for the item or data source 'http://win-lnj1eq8qsfv:16350/PowerPivotTestSite/PowerPivot Gallery/Sum of Sales Quota.xlsx'. Verify that the connection information is correct and that you have permissions to access the data source.</Message>
<MoreInformation>
<Source>Microsoft.ReportingServices.ProcessingCore</Source>
<Message msrs:ErrorCode="rsErrorOpeningConnection" msrs:HelpLink="http://go.microsoft.com/fwlink/?LinkId=20476&EvtSrc=Microsoft.ReportingServices.Diagnostics.Utilities.ErrorStrings&EvtID=rsErrorOpeningConnection&ProdName=Microsoft%20SQL%20Server%20Reporting%20Services&ProdVer=1.0" xmlns:msrs="http://www.microsoft.com/sql/reportingservices">Cannot create a connection to data source 'TemporaryDataSource'.</Message>
<MoreInformation>
<Source>Microsoft.AnalysisServices.AdomdClient</Source>
<Message>A connection cannot be made. Ensure that the server is running.</Message>
<MoreInformation>
<Source>Microsoft.AnalysisServices.SharePoint.Integration</Source>
<Message></Message>
<MoreInformation>
<Source>Microsoft.AnalysisServices.SharePoint.Integration</Source>
<Message>The PowerPivot service application could not connect to the Analysis Services instance.</Message>
</MoreInformation>
</MoreInformation>
</MoreInformation>
</MoreInformation>
</MoreInformation>
<Warnings xmlns="http://www.microsoft.com/sql/reportingservices" />
</detail>

Answer 1

Basically if you read through the error you can see that it cannot open a connection to the data source TemporaryDataSource:
<Message msrs:ErrorCode="rsErrorOpeningConnection" ....
Cannot create a connection to data source 'TemporaryDataSource'.
</Message>
Check that you can access the Datasource manually - the connection string builder dialog should have a 'Test Connection' button.