Question validation ignores parent question/page section condition rules.
When a question is not displayed because its parent section condition attribute in the page flow evalutates to false, the question level validation is still enforecd.
For example, take a drop down with a ? set as default. If this questions partent (or grandparent) section (pageSection or questionSection) has a condition that evaluated to false, the drop down will not appear on the page, however the page will still check the question value when submitted, and with it defaulting to ? it will generate a required error. Meaning the page flow cannot progress - the field is required, but not visible to set.
ie
<!-- Employers Liability circumstances -->
<questionSection condition="m:test(section[id='Trade']/attribute[id='EL_Available']/value[.='Yes'])">
<question title="Do you have a statutory exemption from Employers' Liability Insurance?" binding="/section[id='Trade']/attribute[id='ELStatutoryExemption']" styleClass="mainQuestion" renderHint="radio">
<hintText>
<![CDATA[The following employers are exempt: <br /> * family businesses, however, this exemption does not apply to family businesses which are incorporated as limited companies; <br /> * companies employing only their owner where that employee also owns 50% or more of the issued share capital in the company. <br /> Other companies and organisations may also be specifically exempted, please refer to the HSE website <a href="
http://www.hse.gov.uk/business/elci.htm">
http://www.hse.gov.uk/business/elci.htm</a> for further information.]]>
</hintText>
</question>
<question title="Do you have cover elsewhere for your Employers' Liability?" binding="/section[id='Trade']/attribute[id='ELCoveredElsewhere']" styleClass="mainQuestion" renderHint="radio"/>
</questionSection>