[otrs] Sysconfig : how to activate greyed option

Hi there I like to use the field Ticket::Frontend::AgentTicketQueue###HighlightColor1: but it is greyed Any idea how I could make it available? Many thanks Philippe Martignier Communications Division Customer Service Section Email : Philippe.Martignier@wipo.intmailto:Philippe.Martignier@wipo.int Phone : 00 41 022 338 72 36 Building : GB II Office : 0,3 World Intellectual Property Organization Disclaimer: This electronic message may contain privileged, confidential and copyright protected information. If you have received this e-mail by mistake, please immediately notify the sender and delete this e-mail and all its attachments. Please ensure all e-mail attachments are scanned for viruses prior to opening or using.