Answer:
Most likely the countries already had an existing alliance.
Step-by-step explanation:
They had shared a common border for decades which does not support any full interest of Germany siding with Austria-Hungary. They were already part of an alliance together, the Triple alliance along with Italy. Germany was already part of the scramble for Africa and Austria-Hungary wasn't interested in a colonial empire and didn't have the navy to support one. And neither of the countries were blamed for his death, Austria-Hungary blamed Serbia for the death, which they may have been. Hopefully this helps :)