[xml] repeating elements

I have created a schema that with a complex type that contains a few
html like tags:

<xsd:complexType name="notesText" mixed="true">
	<xsd:sequence minOccurs="0" maxOccurs="unbounded">
		<xsd:element name="b" type="xsd:string" minOccurs="0"/>
		<xsd:element name="i" type="xsd:string" minOccurs="0"/>
		<xsd:element name="p" type="notesText" minOccurs="0"/>
		<xsd:element name="br" minOccurs="0">
			<xsd:simpleType>
				<xsd:restriction base="xsd:string">
					<xsd:length value="0"/>
				</xsd:restriction>
			</xsd:simpleType>
		</xsd:element>
		<xsd:element name="a" minOccurs="0">
			<xsd:complexType mixed="true">
				<xsd:attribute name="href" type="xsd:string" use="required"/>
			</xsd:complexType>
		</xsd:element>
		<xsd:element name="ul" minOccurs="0">
			<xsd:complexType>
				<xsd:sequence maxOccurs="unbounded">
					<xsd:element name="li" type="notesText" minOccurs="0"/>
				</xsd:sequence>
			</xsd:complexType>
		</xsd:element>
     </xsd:sequence>
</xsd:complexType>

As you can see, the type is simple and does exactly what I want...
If I put this inside an element and create an stylesheet using
<xsl:copy-of> I get the desired result of working html code...

HOWEVER, using this definition none of the html editors I have used
lets me add the same html-like-tag two times in a row with text in
between them...

If my element contains:
----------------
This is some <b>text</b> with <i>html</i> tags on it.
----------------

Everything works perfect...BUT if after that I want to add <i>another
italics</i>, the editor won't let me... If I use a raw text editor,
then I can add it, and the instance is valid, but any xml editor that
helps with tag addition will not let me add the second <i> after I
have used one.

However, if I have some other html-like-tag between the two <i>, then
there is no problem...

Does anyone know why???
I have tried adding <sequence minOccurrs=0" maxOccurrs="unbounded">
surrounding all the html-like elements, but that does not work
either...