Placing a file in Different Directories using Dynamic Configuration

I am using following UDF for my requirement and choosing ASMA in channel, here I am using both filename as well as directory dynamically.

public String setFileName(String input1, String input2, String input3, Container container) throws StreamTransformationException{

String filename = new String("");

String directory = new String("");

DynamicConfiguration conf1 = (DynamicConfiguration) container.getTransformationParameters().get(StreamTransformationConstants.DYNAMIC_CONFIGURATION);

DynamicConfigurationKey key1 = DynamicConfigurationKey.create("http:/"+"/sap.com/xi/XI/System/File","FileName");

DynamicConfiguration conf2 = (DynamicConfiguration) container.getTransformationParameters().get(StreamTransformationConstants.DYNAMIC_CONFIGURATION);

DynamicConfigurationKey key2 = DynamicConfigurationKey.create("http:/"+"/sap.com/xi/XI/System/File","Directory");

Date dNow = new Date( );

      SimpleDateFormat ft =

      new SimpleDateFormat ("yyyyMMdd_HHmmssSSS");

filename = ft.format(dNow)  +"_"+input1+ "_WO_"+ input2 +  "_" + input3 + ".XML";

conf1.put(key1,filename);

if(input1=="CR")

{

directory = directory1;

}

else

{

if(input1 =="UP")

{

directory =  "directory2";

}

}

conf2.put(key2,directory);

return "";

}

I am getting floowing error

Transmitting the message to endpoint <local> using connection SOAP_http://sap.com/xi/XI/System failed, due to: com.sap.engine.interfaces.messaging.api.exception.MessagingException: com.sap.aii.adapter.file.configuration.InvalidDynamicConfigurationValueException: The Adapter Message Property Directory provided in the message header has an invalid value: ''

Please Help....