[otrs] AgentTicketCustomer => Customer ID is mandatory

Hello, after updating to OTRS6 the Customer Number in AgentTicketCustomer seems to be mandatory. I checked the code, and if remove readonly="readonly" then it works like i want. How can i fix this with sysconfig? [% IF Required %]<span class="Marker">*</span> [% END %][% Translate("Customer ID") | html %]:</label> <div class="Field"> <input type="text" name="CustomerID" id="CustomerID" value="[% Data.CustomerID | html %]" readonly="readonly" class="W75pc[% IF Required %] Validate_Required[% END %] [% Data.CustomerIDInvalid | html %]"/> [% IF Required %] <div id="CustomerAutoCompleteError" class="TooltipErrorMessage"><p>[% Translate("This field is required.") | html %]</p></div> <div id="CustomerAutoCompleteServerError" class="TooltipErrorMessage"><p>[% Translate("This field is required.") | html %]</p></div> [% END %] Thanks, Mario