Oracle Message LPX-00103 - document structure does not match DTD

ERRORdocument structure does not match DTD
CAUSEValidity Constraint 3 failed: An element is valid if there is a declaration matching elementdecl where the Name matches the element type, and one of the following holds: * The declaration matches EMPTY and the element has no content * The declaration matches children and the sequence of child elements belongs to the language generated by the regular expression in the content model, with optional white space (characters matching the nonterminal S) between each pair of child elements. * The declaration matches Mixed and the content consists of character data and child elements whose types match names in the content model.* The declaration matches ANY, and the types of any child elements have been declared.
ACTIONCorrect the document.