因为昨晚我加班了。 The reason why it isn't “因为我昨晚上班（工作）了” but “因为昨晚我加班了” is： in my opinion,one always works on the daytime,if somebody worked at some night ,that means he 加班了（work overtime）. if he always works at night , the sentence that you put would be "因为我昨天上了夜班"

"because i worked last night" "因为我昨晚在工作 因為我昨天晚上在工作 ( thes sentences are slicely mistakes on ”在“ , and should be removed it will be okay" becuz, the word "在” is use for doing something, wether doing something in present or in the past also can use "在“ to express. but your sentence is Because i worked last night>>>> it doesn't carry out any sence of continueing form, and this sentence is simplily a narrative-sentence. here you go, you can say 因為我昨天晚上工作（上班） 因為我昨夜上班 因為昨夜我工作（上班） 因為昨晚我上班（工作） 因為昨天晚上我上班（工作） all those are correct. but, becareful not to ad ”在“ , and the meaning can change to be because i was working last night = 因为我昨晚在工作 (因為我昨天晚上在工作) hope it helps!

“因为我昨天上夜班。” 或者就说“我昨天晚上在工作”就可以。

因為我昨天晚上在工作 because i worked last night

In mandarin is "因为我昨晚在工作。"