The Python library we use attempts to validate the data in your xml data source file against the xsd schema file indicated within your xml code. That validation is failing.
As a workaround, remove the schema declaration. Xcalar doesn't need it to work with your data. Instead, it builds the schema on the fly through parsing the data. For a longer term solution, please message me privately to supply a sample I can use to replicate and explore the issue further.
Hope this helps! Let me know if you have further questions about this.