Dedonus said
First, you still have a military alliance with the Ottoman Empire, so its bad taste declaring war on the Ottomans. Second, while your rulers might be willing to join the war against the allies, your subjects will be the ones who will be fighting the war. Austria just got out of the war. I doubt they would want to get back into it, especially against their "old" allies.
I'm sorry, but when has war stopped in this RP? Shouldn't every single country be in a state of open rebellion by now?