ok, here is what happened, i have made a custom ERC(CREATED IN DAZ STUDIO ITSELF) that link between V4 and a conforming item. The ERC work perfectly not untill i saved the conforming item into library. When i load it back and reconform to V4, the ERC is not working anymore.( that is, when i change the master dial in V4, the slave dial in conforming figure not changing simultanously anymore)

this conforming figure(cr2 format) is for use in poser only, all the ERC are working perfectly in poser, but strangely some failed in daz studio. so i have to make new ERCs inside daz itself to replace the failed ERC, and save it in daz format for daz users. I wouldnt go that far if initially all the ERCs works fine in daz as in poser.