<label class=" control-label sr-only" for="ORDERS[order_lastname]">[[%register.lastname]]
<span class="error">[[!+reg.error.ORDERS[order_lastname]]]
</span>
</label>
<div class=" input-group">
<span class="input-group-addon">
<i class="oi oi-people"></i>
</span>
<input class="form-control" type="text" name="ORDERS[order_lastname]:required" id="order_lastname" value="[[!+reg.ORDERS[order_lastname]]]" placeholder="Last name"/>
</div>[[!Register? &submitVar=`registerbtn` &activation=`1` &activationEmailTpl=`lgnActivateEmailTpl` &activationEmailSubject=`Please activate your account!` &activationResourceId=`54` &submittedResourceId=`53` &useExtended=`1` &emailField=`order_email` &usergroups=`Members` &validate=`nospam:blank, username:required:minLength=^6^, password:required:minLength=^6^, password_confirm:password_confirm=^password^, ORDERS[order_firstname]:required ` &placeholderPrefix=`reg.` ]]
<div class="form-group ">
<label class=" control-label sr-only" for="ORDERS[order_firstname]">[[%register.fname]]
<span class="error">[[!+reg.error.ORDERS[order_firstname] ]]
</span>
</label>
<div class=" input-group">
<span class="input-group-addon">
<i class="oi oi-people"></i>
</span>
<input class="form-control" type="text" name="ORDERS[order_firstname]:required" id="order_firstname" value="[[!+reg.ORDERS[order_firstname] ]]" placeholder="[[%register.fname]]"/>
</div>I think you may have a situation where your extended field has the same name as a normal field. Is the data in both the same? I would say try to give that extended field a unique name and then the problem may be gone...
&validate=`nospam:blank, username:required:minLength=^6^, password:required:minLength=^6^, password_confirm:password_confirm=^password^, `
&validate=`nospam:blank, username:required:minLength=^6^, password:required:minLength=^6^, password_confirm:password_confirm=^password^, ORDERS[order_firstname]:required`