unexpected results using XP_DIRTREE

I am working on a procedure that will check directories using `xp_DirTree` to confirm that the correct number of files have been generated by an earlier process.

Unfortunately my query (the last part) is giving incorrect results

    declare @DateOffset int
    set @DateOffset=6
    -- Create a table variable to store user data
    DECLARE @myTable TABLE
    (
        docID INT IDENTITY(1,1),
        docRef VARCHAR(50),
        YPTMPID varchar(3),
        saveDir VARCHAR(4000),
        totalLettersExpected int,
        actualLetters int 
    );
    insert @myTable SELECT docRef, YPTMPID,
     saveDir=max(Save_Directory) + cast(YEAR(GETDATE()-@DateOffset) as varchar(4)) + '\'  + datename(month, GETDATE()-@DateOffset) + '\'+SUBSTRING(CONVERT(CHAR(20), GETDATE()-@DateOffset, 101),4, 2) + '.' + LEFT(CONVERT(CHAR(20), GETDATE()-@DateOffset, 101), 2)+ '.' + SUBSTRING(CONVERT(CHAR(20), GETDATE()-@DateOffset, 101),7, 4),
     COUNT(*) as 'Total Letters', null
      FROM [alpsMaster].[dbo].[uExtractMonitor]
      group by docRef, YPTMPID
      order by 1,2
    select * from @myTable
    -- Get the number of rows in the looping table
    DECLARE @RowCount INT, @SQL nvarchar(4000), @LoopSQL nvarchar(4000), @Date varchar(20)
    set @Date=rtrim(CONVERT( CHAR(12), getDate()-@DateOffset, 106)) --'29 Oct 2013'
    SET @RowCount = (SELECT COUNT(docID) FROM @myTable) 
    -- Declare an iterator
    DECLARE @I INT
    -- Initialize the iterator
    SET @I = 1
    -- Loop through the rows of table @myTable, and for each docRef, check the file directory for the correct number of files
    WHILE (@I <= @RowCount)
     BEGIN
            DECLARE @docRef VARCHAR(10), @saveDir VARCHAR(500), @letterCount int
            -- Get the data from table and set to variables
            SELECT @docRef = docref FROM @myTable WHERE docID = @I
            SELECT @saveDir = saveDir FROM @myTable WHERE docID = @I  
         update @myTable set actualLetters = 0 where docRef=@docRef
         create table #files (subdirectory varchar(100), depth int, [file] int)
         insert into #files  EXEC master.sys.xp_dirtree @saveDir,0,1; 
         select @letterCount = COUNT(*) from #files 
         drop table #files
         update @myTable set actualLetters = @letterCount where docRef=@docRef
         -- Increment the iterator
         SET @I = @I  + 1  
     END
    select * from @myTable

Unfortunately in my last WHILE loop something is going wrong. The numbers put in theactualLetters column should match the column totalLettersExpected

On the network the number of files does match the column totalLettersExpected so where have I gone wrong, and is there a better, more robust way of doing this?

thanks