Inflatable air bed deflates after a few hour

<p>I purchased this camping bed a year ago. I used it about 4 times and it always deflates when my son sleeps on it. My 3 year old son used it and we only use it indoors. He weighs about 13KG only.</p> <p> </p> <p>Is this normal? I also have an air pump from the same manufacturer and it works just fine.</p> <p> </p> <p>It just feels like a waste of money!!!</p>