In advanve booking

good morning from Milan. My name is Lino and I’m planning a trip in Turkey and Georgia. I’d arrive in Georgia in late April, cross the border to Kars, and then from Kars I’d like to take the famous Dogu Express to Ankara. I was going to make the quotation with the TCDD site, but it says that in selected dates there are no trains. My dates is 27th of April. Can you help me somehow?