If I recall correctly (I may be wrong), IIS by default is 64 bit and expects 64 bit processes. To run 32 bit DLLs you need to set the app pool for it to be explicitly 32 bit. Dont change the default app pool, you'll kill the other DLLs on the server. Create a new one for your app and set it to 32 bit.
https://webconnection.west-wind.com/docs/_24d0uty4k.htm
https://webconnection.west-wind.com/docs/_24d0uty4k.htm

