ORA-30936 error updating a SQLType="CLOB" field

Question

PROBLEM:
I'm using Oracle 9.2.0.4 on Solaris 64bit.
My table is:
create table cd3_tab(id number primary key, cd xmltype)
xmltype column cd
xmlschema "cd3.xsd" element "CDS"
I have inserted one xml file into cd field.The id has value 2.
Below you can find the schema.
Using:
update cd3_tab cd=updateXML(cd,'/CDS/CD[1]/Description/text()','xxx')
where id =2
i get: ORA-30936 Maximum Number(1) of 'Description' XML node elements exceeded.
As you can see in the schema the Description filed is defined with the xdb:SQLType="CLOB" directive because it can be longer than 4k.
If i do:
update cd3_tab cd=updateXML(cd,'/CDS/CD[1]/Title/text()','xxx')
where id =2
i got the same error and THIS IS BIZARRE always on the 'Description' node even if my update now in on the 'Title' filed.
OTHER TEST
==========
Also the same error occurs when i select the Description node:
select extract(cd,'/CDS/CD[1]/Description/text()') from cd3_tab where id=2;
if i use : select extract(cd,'/CDS/CD[1]/Description') from cd3_tab where id=2;
i got no error.
SCHEMA
======
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xdb="http://xmlns.oracle.com/xdb">
<xs:element name="CDS">
<xs:complexType>
<xs:sequence>
<xs:element ref="CD" minOccurs="1" maxOccurs="unbounded" xdb:SQLInline="false"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="CD">
<xs:complexType>
<xs:sequence>
<xs:element name="Title" type="xs:string"/>
<xs:element name="Artist" type="xs:string"/>
<xs:element name="Website" type="xs:anyURI"/>
<xs:element name="Description" xdb:SQLName="DESCRIZIONE_T" xdb:SQLType="CLOB"/>
<xs:element name="Songs">
<xs:complexType>
<xs:sequence>
<xs:element name="Song" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="Title" type="xs:string"/>
<xs:element name="PlayingTime" type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>

Answer 1

Upgrade to 9.2.0.5.0 since 9.2.0.2.0 is not supported for XMLType. Also try OCI rather than thin dirver.