This usually means that one of your data fields for a required element is null. Check your data field against the schema to make sure they match.
Also, you can try to set <ignorecontent>false</ignorecontent> to true. This will ignore the data in the fields, but will perform tag/element validation only.
I have a flatfile schema with fixed length.
There are some mandatory fields in it, where an error is need to be thrown if they are null.
After convert to values it shud throw the error, but its not.
Is there any service to validate this and throw an error.