Problem facing in Dynamic configuration in SAP PI 7.3

Hello,

I am doing dynamic configuration in sap pi 7.3. I am using the following UDF.

String devFileName="'a.vc'";

DynamicConfiguration conf = (DynamicConfiguration) container.getTransformationParameters().get(StreamTransformationConstants.DYNAMIC_CONFIGURATION);

DynamicConfigurationKey FileName = DynamicConfigurationKey.create("http:/"+"/sap.com/xi/XI/System/File","FileName");

conf.put(FileName, devFilename);

I am using this UDF in message mapping and mapped this UDF in the message header.

I have selected the adapter specific message attribute in receiver communication channel also.

Still I am getting the folowing error.

MP: exception caught with cause com.sap.engine.interfaces.messaging.api.exception.MessagingException: com.sap.aii.adapter.file.configuration.DynamicConfigurationException: The Adapter Message Property 'FileName' was configured as mandatory element, but was not supplied in the XI Message header

Exception caught by adapter framework: The Adapter Message Property 'FileName' was configured as mandatory element, but was not supplied in the XI Message header

'Transmitting the message to endpoint using connection File_http://sap.com/xi/XI/System failed, due to: com.sap.engine.interfaces.messaging.api.exception.MessagingException: com.sap.aii.adapter.file.configuration.DynamicConfigurationException:  The Adapter Message Property 'FileName' was configured as mandatory element, but was not supplied in the XI Message header.

Please help me what to do.

Thanks & Regards,

Moumita