Re: voltage divider circuit
Your problem is some thing to do with load.
Ckeck your load impedance/load resistance
In the fallowing ckt, with no load you will get 5v acroos the output
But as you decrease the load, say RL=2K, the effctive resister bridge becomes 10V, 1K, 0.67K(1K||2K) and you will get 3.99V. As you decrease the load resistance, the effective output voltage decreases.I think in your case the load is close to 1K, where your getting slighly lower voltage than 5V
Generally the resister bridges are used for high impedance constant loads.
So tell me what your exact load is, then we can try using high resister or going for zener regulation, which is the next better solution