RNA isolation failure

[Lin Xiao]

I use Single-Step RNA Isolation By Guanidinium mix (GITC)
described by Chomczynski. It seens OK for me. Recently I cannot 
see the RNA pellet after acid phenol-chloroform extraction and alcohol 
(2-2.5 vol) or isoprepanol (1-1.5 vol) precipitation with 1/20 vol of 3 M 
NaOAC, and can see nothing in 1% formaldehyde-agarose gel, when I use 2 
million neutrophils or 10 times more cells from human being (fresh). All 
of the chemicals including phenol, pH of phenol, alcohol, etc had checked 
but nothing was wrong. Please tell me what's wrong here and any suggestions 
or hits to me. 

Thanks..

Linxiao

Dept. Biochemistry
Faculty of Medicine
National University of Singapore