Remembering names is often the ____ to a friendship,a closed

Remembering names is often the ____ to a friendship,a closed business and a new partnership.
A.ticket B.success
请问答案为什么不能填A?
我查过词典：牛津双解：
ticket for/to sth.
eg She hoped that getting this job would finally be her ticket to success.她希望得到这份工作终将会使她踏上成功之途。
secret of
(高一课本）When asked about his secret of success,he owed much of his success to his wife and children.
(牛津）Careful planning is the secret of success.仔细计划是成功的诀窍。