。
But unluckily, the match was called off because of the rain.
Literal
But unlucky [genitive-の] rain [because-of-で] match [topic-は] cancellation became.
A very common sports/weather disappointment. あいにく (生憎) is a formal/polite adverb for 'unfortunately,' and あいにくの [noun] is the attributive form — 'an unfortunate X,' 'an unlucky X.' The で here is the causal/instrumental で ('because of,' 'due to'). 中止になる is the standard collocation for 'become cancelled' — Japanese prefers intransitive 'become X' over passive 'be X-ed' for events of this kind.