laplace transform of $ u(t-1)sin(\pi t) $

Question

I'm having difficulties with finding laplace transform of $ u(t-1)sin(\pi t) $

The answer I got is $\frac{\pi e^{-s}}{s^2+\pi^2}$, but the correct one is $\frac{-\pi e^{-s}}{s^2+\pi^2}$ ,

I don't understand where does the negative sign come from.

thank you