山东省平度市某村民问:我五年前从张某处购得市区一处房产,当时只签订了买卖合同,因疏忽未办理变更登记。现我找张某办理变更登记手续,可张某以当时卖得贱了为由,要求我再给他5000元钱,否则就不帮我办理相关手续。请问,我未办理登记手续购房行为是否有效?我该怎么办?答:1994年7月5日颁布、2007年8月30日修订的《中华人民共和国城市房地产管理法》第61条规定,房地产转让或者变更时,应当向县级以 Pingdu City, Shandong Province, a villager asked: I bought a downtown area from Zhang somewhere five years ago, was only signed a contract for the sale, because of failure to change registration. Now I find Zhang for change registration procedures can Zhang sold at the time was cheap because I asked him to give him 5,000 dollars, or do not help me handle the relevant procedures. I would like to ask, I did not apply for registration of the purchase is valid? What should I do? A: July 5, 1994, August 30, 2007 revised “Urban Real Estate Management Law of the People’s Republic of China,” Article 61 provides that real estate Transfer or change, it should be to the county level