缺乏确凿的证据 meaning in English

the absence of definite proof

But because vasari relied on anecdotal evidence , there was always doubts about the identification , and leonardo is not known to have made any notes about the model ' s identity himself
但由于瓦萨尼的结论缺乏确凿的证据，这个说法一直受到怀疑。而达?芬奇本人也未对画中女子的真实身份进行过任何确认。
But because vasari relied on anecdotal evidence , there was always a doubt about the identification , and leonardo is not known to have made any notes about the model ' s identity himself
但由于瓦萨尼的结论缺乏确凿的证据，这个说法一直受到怀疑。而达?芬奇本人也未对画中女子的真实身份进行过任何确认。