Adobe Acrobat 8 unable to load plug-in in Window Vista

Question

I have developed a plug in for Adobe Acrobat, but Abode Acrobat unable to load the plug in. I try to troubleshoot the problem by putting a messagebox in the PIHandshake function.
Noticed that, the function is not being called by Adobe Acrobat when Acrobat app is launched.
When Adobe Acrobat is launching, I able to see the my plug in's name is display on the splash screen.
Below is the environment info:
a. Adobe Acrobat 8 Standard Version 8.1.3
b. Window Vista Business
I try to put a messagebox in function ACCB1 ASBool ACCB2 PIHandshake(Uns32 handshakeVersion, void *handshakeData), the Adobe Acrobat application didn't call this function.
ACCB1 ASBool ACCB2 PIHandshake(Uns32 handshakeVersion, void *handshakeData)
AVAlertNote(" PIHandshake");
I have reinstalled Adobe Acrobat software, but the problem still happend. Is there anyone can guide me what is wrong, what possible things that may cause the application unable to load the plug in
and what steps should i need to do next?

Answer 1

Your guidance did help me a lot in troubleshooting the problem. Thanks all of you.
Findings:
I use a sample plug-in, the acrobat is able to load it out. Then, I use depend.exe to compare the sample plug-in with my plug-in, I noticed that my plug-in does not have PlugInMain entry point function.
The reason is I compile my plug-in as release version and did not put a command line /EXPORT:PlugInMain under [AppProject]->Properties->Linker->Command line.
The second reason is my plugin - the one with the problem has been cached in VirtualStore directory, and i didn't realize it. Therefore, everytime i run acrobat app, it always load the old api (no PlugInMain) from the VirturalStore directory. After delete the old file. Then, Acrobat is able to load my new api from c:\Program Files\Adobe\Acrobat 8.0\Acrobat\plug_ins.
VirtualStore Directory:
C:\Users\[User Name]\AppData\Local\VirtualStore\Program Files\Adobe\Acrobat 8.0\Acrobat\plug_ins