How do I restrict the length of character in XML Schema?

I have not dabbled in xml much and have been trying to google my way out of a little of trying to restrict the maximum of characters a user is allowed to enter into a box.

Here is my current code:

    <xs:complexType name="reason">
      <xs:attribute name="reason">
        <xs:simpleType>
          <xs:restriction base="xs:string">
            <xs:maxLength value = "75"/>
          </xs:restriction>
        </xs:simpleType>
      </xs:attribute>
  </xs:complexType>

The field name on our database is called reason and I have defined the character length to nvarchar(75).

I am also trying to use same name as the attribute name on the xml.

What is happening currently is that when a user enters more than 75 characters, an error message ensues.

This tells me that the restrictions on my xsd file is not working correctly.

Any ideas what I am missing?