DOT BLOT for pcr product - No result obtain (Nov/23/2010 )

i want know solve for the problem imake dot blot for pcr product using biotinylated probe which make diagnosis of TB by pcr dot blot and iwant know if using Dithitheritol for liquefication of sputum sample instead of NALC/Naoh effect in the result
thanks

you must sure about the way of extraction of sample which mey be present problem in extraction