[Zoxeeoy]

I think that this is one of those cases where here will be a disagreement between the various traditions of Buddhism.

Below is a short teaching by Kalu Rinpoche and link that is very clear in the TB belief of past and future lives.

Understanding the Need for Spiritual Practice
A Teaching by Kyabje Dorje Chang Kalu Rinpoche
Kagyu Thubten Chöling Monastery, 1986

In order to practice the Dharma taught by the Buddha it is necessary, at the outset, to establish confidence in its validity.

First we must understand that we have had countless lives in the past and will continue to have countless lives until we attain the level of a Buddha or Bodhisattva. Belief in the existence of previous and future lives gives rise to confidence in the truth of karma, the effects of actions. This confidence is based on understanding that unvirtuous actions lead to suffering and virtuous actions lead to happiness. Without this conviction, we will not abandon unvirtuous actions or perform virtuous ones.

We can reach this conviction by examining the signs of the workings of karma in the world around us. Although we are all born as human beings, each person experiences different circumstances, such as a long or short life, mental happiness or misery, and wealth or poverty. These variations in individual circumstances arise through previous karma accumulated in former lifetimes. Even animals have a sense that actions lead to results. They know enough to look for food when they are hungry, water when they are thirsty, and shade when they are hot.

If one has no confidence in the existence of past or future lives or in the truth of the effects of karma, then one will have no appreciation of Buddhism or any other religion. The practices of all religions are based on the intention to benefit oneself and others in a future existence.

The Buddha taught that sentient beings are subject to 84,000 mental afflictions; to remedy them, he gave 84,000 profound and extensive teachings. The point of all these teachings is to benefit the mind. One's body and speech will automatically derive benefit since the mind is like the master, and the body and speech are like its servants. For example, through thoughts of generosity, we perform acts of generosity; and because of angry thoughts, we use harsh words or act unkindly. The mind is the source of the action while the body and speech enact the mind's intentions. For instance, today you had the thought, "I must go to Kagyu Thubten Chöling to hear the Dharma," and in response to that thought, your body and speech somehow managed to accomplish this.

If one practices the Dharma correctly, then the four types of obscurations that veil the nature of the mind—ignorance, habitual patterns based on dualistic perception, mental afflictions, and karma—are removed. Complete elimination of these obscurations—known in Tibetan as sang—causes the inherent qualities of the mind's nature to manifest fully and spontaneously. This manifestation of the qualities and wisdom of the mind is called gye in Tibetan. Together these two form the word sang gye, which means Buddha or Buddhahood, the ultimate attainment.

It is necessary to practice Dharma because we are subject to impermanence. Born from our mother's womb, we go through childhood, mature, grow old, get sick, and eventually die. None of us can avoid birth, old age, sickness, and death. We have no control over this. That is why we need to practice the Dharma.

Since no one lives forever, we have an underlying awareness that we are going to die. But we have only the idea "I'm going to die." We don't remember the suffering, fear and difficulty we experience at the time of death. We don't really understand the nature of death because we don't understand the meaning of Dharma.

If our whole existence just disappeared at death like a flame that has been extinguished, or like water that evaporates, then everything would be fine. But the mind's nature is empty, clear, and unimpeded. Because it is empty it does not die. Our mind does not disappear, but goes on after our physical death to experience the confused appearances of the interval between death and the next rebirth (Tib. bardo). We then take rebirth in one of the six states of existence. This cycle repeats again and again. Since the nature of cyclic existence is impermanence, it is a source of only suffering and not happiness.

continued at the link:

http://www.kagyu.com/en/introduction/a-teaching