temperature not rising

I finished my 3d printer and was ready for my first print when I got stuck. I started the repetier host(that I use for printing), and the bed and extrusion are starting to heat up. After couple of minutes the temperature stops rising for both bed and extruder. The bed stops around 80 and extruder around 28. Anyone has idea what could be the problem?

Most likely the heater element is loose in the block.There is a small set screw to tighten the heater to the block and check the thermistor is making good contact to this block or some cases the nozzle

I can't speak to the heat-bed, i have never tried to go above 80. but a couple things to check on the hot-end.

1) make sure that your thermistor (the glass ball on the end of two little wires) is firmly pushed into your hotend.
2) make sure that the fan on the heat break is off when it is pre-heating. I had a similar problem, where my fan was cooling my hotend faster than it could heat.
3) try a new heater cartridge/resistor, (the can shaped thing in your hotend). I'm on my second, you just sometimes get a defective one, or one will go bad, i would advise buying a 3 pack off ebay.
4) Don't trust your printer's layout, if you have a way to independently verify the temperature of the hot-end, like with an IR thermometer or a multimeter and thermal-couple. If the temperatures between what your instruments see and what the printer see are more than 25% different, then that means that you may need a new thermistor, or your firmware is set to a different type of thermistor (like a 150k instead of a 100k)