ADL default merge copy activity
<p>I am using the "MergeFile" in default copy activity. My source is azure blob storage and my destination is ADL Store. However, I get the following error.</p>

<blockquote>
  <p>ErrorCode=UserErrorFileNotFound,'Type=Microsoft.DataTransfer.Common.Shared.HybridDeliveryException,Message=Cannot
  find the 'Azure Data Lake Store' file.
  ,Source=Microsoft.DataTransfer.ClientLibrary,''Type=System.Net.WebException,Message=The
  remote server returned an error: (404) Not Found.,Source=System,'.</p>
</blockquote>

<p>How do I specify the file name for output to resolve this error?
I am following this documentation page for default copy activity. 
<a href="https://azure.microsoft.com/en-us/documentation/articles/data-factory-azure-blob-connector/" rel="nofollow">blob connector</a>.  </p>

<p>I have also tried with using a specific file name at output dataset.</p>

<p><strong>Update:</strong>
If I change the destination to azure blob then i do not get that error but another error related to xml which I believe is a user error.</p>

<blockquote>
  <p>Copy activity encountered a user error:
  ErrorCode=UserErrorSourceDataContainsMoreColumnsThanDefined,'Type=Microsoft.DataTransfer.Common.Shared.HybridDeliveryException,Message=Error
  found when processing 'Csv/Tsv Format Text' source
  '01/1001464881_1001464795_2015-01-01_1.13.05.152__1000.xml' with row
  number 1: found more columns than expected column count:
  1.,Source=Microsoft.DataTransfer.Common,'.</p>
</blockquote>

<p>My goal is to merge xml files from directory and sub-directory into single big file.</p>