ORA-00911: invalid character?

ORA-00911: invalid character?

My code gives ORA-00911: invalid character at XDocument doc=
Document.Load(crtCommand.ExecuteScalar().ToString());*
Any idea!
using (OracleConnection conn1 = new OracleConnection(oradb1))
{
conn1.Open();
using (OracleCommand crtCommand = new
OracleCommand("SELECT
dbms_metadata.get_sxml('VIEW','VIEW_TBL_A') FROM
dual;", conn1))
{
XDocument doc =
XDocument.Load(crtCommand.ExecuteScalar().ToString());
XNamespace ns = "http://xmlns.oracle.com/ku";
if (doc.Descendants(ns + "COL_LIST_ITEM").Any(c =>
c.Attributes().Any()))
{
MessageBox.Show("COL_LIST has value");
}
else
{
MessageBox.Show("COL_LIST has no value");
}
}
}