Sallie

Hello all, Just a quick question. I've purchased from the L2 coin shop the Sayha's Will (1day) for 120 coins. I've notived when i used it that I only have 306% exp boost. Sayha's Grace is 306% exp boost (2types it says) and 25% exp clan boost. My sayha's Grace bar is full at the moment, and I really thought it could add up with the Sayha's Will, giving me 300+300= 600%exp boost. Did i miss something here, do they not work together or what? Seems to me like i only have the Sayha's Will running for one day... Any of the Devs care to explain, or a fellow player, it would be much appreciated because I'm fairly new to this. Kind regards, Sallie.