Problem Reading a Text File Backwards C#

[stoogots2]

I have written a Windows App in C# that needs to read a text file over the network, starting from the end of the file and reading backwards toward the beginning (looking for the last occurrence of a couple of strings in one line of text). I do not want to read the entire file, as it is very large, on a highly utilized server, and is updated with hundreds of lines of text every second. So since I am reading backwards, I do a seek, then read, then encode the byte array as a string, split the string into an array of lines, then iterate and search through the string array. My problem is that since the first or 0 element of my string array will almost always be an incomplete line, to ensure 100% reliability I need to adjust the next seek so that I read the entire line that was incomplete/truncated on the last read (it would ideally be the final element of the next string array after the read,encode,spl it). So everything works great except that I can't seem to adjust the Seek to always read the whole truncated line. Most of the time it works, but not 100%, and therefore is useless :). I must be doing something wrong with the counting of the bytes or "\r\n"s. Any reasonable help would be appreciated. Code is below...

 using (FileStream fs = new FileStream(sFullPathAndFileName, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
{
   fs.Seek(iBBFileSize+iBytesPerRead, SeekOrigin.Begin);
   byte[] BBLog = new byte[posBytesPerRead];
   System.Text.ASCIIEncoding enc = new System.Text.ASCIIEncoding();
   //lTotalBytes is a negative number used to offset to the position to start read
   //iBytesPerRead is a negative number
   //posBytesPerRead is the positive version of iBytesPerRead
   //iBR represents bytes read
   while (found == 0 && fs.Position>posBytesPerRead)
   {
     iBR = fs.Read(BBLog, 0, posBytesPerRead);
     lTotalBytes -= iBR;
     BBString = enc.GetString(BBLog);
     BBLines = BBString.Split(new string[] { "\r\n" }, StringSplitOptions.None);
     iBBLineCount = BBLines.Length;
     //Removed string array iteration/parsing
     iFirstlinelength = BBLines[0].Length;
     lTotalBytes += iFirstlinelength;
     fs.Seek(iBBFileSize + lTotalBytes + (2*iBBLineCount), SeekOrigin.Begin);
   }

[stoogots2]

I've taken the out the (2*iBBLineCount ) from the last line (which was the was I originally programmed this), but it still does not seem to work. Very strange, because this looks right to me. One observation is that when I look at my watch window at breakpoints, I see some really strange results, like my string array (BBLines) not being updated every read.