Solution for very short baseline (< 10m)

I couldn't achive a solution for two sites separated ~ 6m away. I tried almost all those options: LC_AUTCLN, LC_HELP, LC_ONLY, L1,L2INDEPEN, L1&L2, L1_ONLY, L2_ONLY. Different results were got with cm-level uncertainity sometimes. The most stable result was obtained when using L2_ONLY choice. But which one is best is still to be studied.