Why won't my Philips tv store the channels?

Since the retune deadlines my tv has to be reinstalled every time I turn it on. It doesn't remember the stored channels, is this a fult or am I doing something stupidly wrong in the reinstall process which I can now do in my sleep. I was advised to reinstall with no aerial in to we the memory but still the same can anybody recommend a solution am getting sick now.
Kind regards mike