can't reach 5v with R2R DAC

Yes they were all high.
Actually, I just built the R2R dac, without op-amps. I wanted to test this part first.
Anyhow, I really need to have a range from 0-5v. It's not for audio. I generate DC signals and control analog synthesizers. Each volt is an octave, so to have 5 octaves i need 5v