append两个数据失败了，数据都是可以正常导入并打开的，也没有移动位置。有大佬知道什么原因吗？
提示：.dta file corrupt
    There was an I/O error.  This suggests the problem is with the device
    rather than the file itself.
.dta file is corrupt
    Pieces in the file are not where they are expected to be.
r(688);