DIY cable problems

[aliman]

Does anyone know if the schematic from Tech Edge, using the MAX 232 is correct. I read in a post someone had mentioned that diode D3 was incorrect.
I built the circuit as shown in their schematic, and I was using EFILive V4 to try and connect to my 1989 5.7L IROC-Z.
I have connected the Tech-Edge circuit to the ALDL connector via home built cable, and the Tech-Edge circuit through a Serial to USB adapter cable made by Prolific Corp. to a Toshiba laptop.
I can't get it to connect ?
Any help would be great !

Aliman
Here is what I'm seeing when I try and connect

1:12.035: Initialising...
21:12.597: Opening COM3 8228,8,N,1
21:12.718: Ready.
21:18.632: Check vehicle interface...
21:18.639: Waiting for Aldl bus silence of at least 50ms...
21:18.687: Requesting Max232 interface to acknowlege: $FF,$55,$AC...
21:18.796: Com timeout: Expecting frame header byte
21:18.800: No response from Max232
21:18.800: Retrying Max232 detection...

21:18.800: Waiting for Aldl bus silence of at least 50ms...
21:18.847: Requesting Max232 interface to acknowlege: $FF,$55,$AC...
21:18.956: Com timeout: Expecting frame header byte
21:18.962: No response from Max232
21:18.962: Retrying Max232 detection...

21:18.962: Waiting for Aldl bus silence of at least 50ms...
21:19.011: Requesting Max232 interface to acknowlege: $FF,$55,$AC...
21:19.120: Com timeout: Expecting frame header byte
21:19.126: No response from Max232
21:19.126: Retrying Max232 detection...

21:19.126: Interface cannot be detected

21:19.153: Scanning for heartbeat and chatter frames...
21:19.153: Waiting for Aldl bus silence of at least 50ms...
21:19.303: Com timeout: Expecting frame header byte
21:19.307: No chatter found