文件读入的问题

sydneyxxy

Dim a(1) As String
Dim aCADdoc As Object '建立Document对象
Set aCADdoc = acadapp.ActiveDocument
a(0) = Str(1)
a(1) = blockrefobj.Handle

Open "c:\testfirst.txt" For Append As #1
Print #1, a(0), a(1)
Close

数组a(),将数值读入a(0),句柄读入a(1)
有时候程序运行没问题,有时候a(1)写进文本文件的却是空值.
请问哪位知道错误原因