[求助]ObjectARX帮助!!!

cyr

我用acedSSGet("I", NULL, NULL, NULL,CurSelSet)求得当前选择集,再求出CurSelSet里的图元ID号,并将他们的ID号存人ObjIdArray(AcDbObjectIdArray ObjIdArray)里,然后通过ID号打开Object,但是只能读不能写,为什么?acdbOpenObject(pObj,eId,AcDb::kForRead)可以,acdbOpenObject(pObj,eId,AcDb::kForWrite)不行