Adding header data to Flat File Send Pipeline

Hi,

I am trying to add header data to flat file Send pipeline in orchestration. Code I am using is as:

 // Add header summary details to pipeline

PipeLineInput.Add(PaymentSummary);

// Execute send pipeline to create a single flat file output

PaymentsOut = null;

Microsoft.XLANGs.Pipeline.XLANGPipelineManager.ExecuteSendPipeline(typeof(XYZ.Training.Lesson4.Pipelines.SendPaymentRecords), PipeLineInput, PaymentsOut);

But, all the time I am encountering ‘Schema not found’ error. Everything works fine with document schema but as I try to add header message data to collection, biztalk thows error.

Can anybody guide me to add header data? I tried using XMLNorma.FlatFileheaderdocumentdata but couldn’t find on which message to use?