Believe, that the error is produced by your ODBC-connector, have you been able to identify, where this error incurred (fieldname, content, length, special characters .....).
Incremental load might be done with a script like:
LOAD key, ... FROM MyData.QVD (QVD);
CONCATENATE (ExistingData) LOAD key, ..... FROM ..... WHERE NOT EXISTS(key);
STORE NewData INTO MyData.QVD (QVD);