〜なくて: not ..., so; without doing

Gives a reason or links a negative state, "because it is not".

Verb or adjective negative 〜ない → 〜なくて. Often a reason for a feeling or a result: 連絡がなくて心配だ. The second part is usually a feeling or state, not a request or intention. Not the same as 〜ないで (without doing).