Simple continuous in this sentence is not wrong necessarily, but it would be a bit awkward in this sentence. The time indicator "at one o'clock" gives a very specific timeframe which makes the simple past more appropriate since it was a one time event. The simple continuous would imply an ongoing action which would change the meaning of the sentence from: "You were here with me (ongoing state) when Daniel called (interrupting single action)." to "You were here with me (ongoing state) while Daniel was calling (repeated or continuous action)."

Hello and good morning Trang. The reason why you got it wrong is because grammatically you have to answer in the tense the question or statement was made in. This is for formal situations. So, because the sentence after the conjunction is in the past simple you must answer in the past simple. Its part of Subject/Verb agreement. "called' is in the third person past simple tense. "you were" is in the second person past simple tense. This is Subject/Verb agreement. "was calling" is in the past continuous tense and thus for it to corelate to the second sentence after the conjunction the second verb would have to also be in the past continuous tense too. Since it is not then it is wrong grammatically in formal situations. Natively it's correct because this is how we naturally speak. We use some tenses interchangeably. So, grammatically you were wrong but natively you were correct. I hope this helps and answers you question and clarifies the difference between formal and native grammatic speech.

Thank all of you for your clear explaination so much

Using "was calling" would be used if something was happening at the time. " Daniel called/was calling you at one o'clock yesterday,WHILE were here with me." I don't know any grammar rules, just that "called" is correct