Agent won't work on new box

Stumped. Checked permissions and access paths.
Moved Domino 6.2 from 270 to 825.

One form has Agent Mgr give "Unable to open file" error whenever we submit form.
Code uses a working directory and attempts to write file.
Code that gives error:
"Declarations"
Const WORKING_DIRECTORY = "/WEB/domino/web/data/domino/HTMLmail/"

"WriteFile"
Function writeFile
        On Error Goto write_File_ERROR
        Dim fileNum As Integer
        fileNum% = Freefile()
        
        If CONVERT_FOR_400 Then
        '       Open FILE_NAME_TEMP For Append As fileNum%
                Open FILE_NAME_TEMP For Append As fileNum%
        Else
                Open FILE_NAME For Append As fileNum%   
        End If

Any help or insight greatly appreciated.