Please describe the problem:
In the schema file, <all> model group has minOccurs="0". and has 3 elements under this all model group. In the instance document, if only two elements are present, then validation should give an error. but libxml2 is not giving any error.

Steps to reproduce:
1. declare an element declaration with <all> model group with minOccurs="0" which has 3 elements.
2. In the instance document give only two elements.


Actual results:
Validation is not giving any error.

Expected results:
Schema validation should give error.

Does this happen every time?
yes

Other information:
Schema script:
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:bar="http://bar">
	<xs:element name="root">
		<xs:complexType>
			<xs:sequence minOccurs="0" maxOccurs="unbounded">
				<xs:element ref="test3"/>
			</xs:sequence>
		</xs:complexType>
	</xs:element>
	<xs:element name="test3">
		<xs:complexType>
			<xs:all minOccurs="0">
				<xs:element name="t3-a"/>
				<xs:element name="t3-b"/>
				<xs:element name="t3-c"/>
			</xs:all>
		</xs:complexType>
	</xs:element>
</xs:schema>


Instance document:

<root xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="D:\TestCases\Bugzilla\BUG_190.xsd">
	<test3>
		<t3-a/>
		<t3-b/>
	</test3>
</root>