External Driver Model DLL issues

I spent a long time in investigating how to code a external driver model DLL files for VISSIM. The information provided in the folder API\DriverModelDLL is limited and was updated at 2005. I did my best to understand the instruction in code and tried to test some DLL files with very simple driver model. Once I run simulation in VISSIM with external driver model DLL files, a error jumped out and told me "Could not retrieve driver model status!". Since the DriverModelDLL API only consist of three functions, I suppose the way main function call those function in DriverModelDLL changed but it was not updated in DriverModelDLL API. I will appreciate if anyone can help me to figure it out. I need to test my own driver model in VISSIM. Thanks. My email is muderx@gmail.com.

You've got the wrong VisSim

Let me make a guess: you want the German traffic simulation software called VISSIM, not the model based development software called VisSim of this site.