DLL error 126 on a DLL using NI-Visa LabWindows 2020

[FrancescoAmbr]

Hello,
I’m working on a project where I need to use a DLL useful for reading and writing to serial port.
I tried in every way to call the DLL through a server I wrote, always using LabWindows, but with the LoadLibrary command I get the error 126, that is "module not found".

In the various attempts at correction I have already tried to :
1) DLLEXPORT
2) Create a new project
3) Debugging in 32 and 64 bits
4) Check that the server worked with a DLL with only one print function (and it works)
5) Create a separate folder so you don’t have names that could create a conflict in the file search
6) Updated NI-Visa to version 21.5

Even searching online I do not understand what is wrong with my code because according to what I found in this community, it should work.

I am patiently waiting for someone to give me a hand in finding the solution to this mystery and I appreciate your answer ahead of time.

[RobertoBozzolo]

I don't understand your reference to VISA when you say you are trying to use a DLL.

If it's VISA functions you want to use, then you do not need to directly access the DLL: if VISA is installed in the system you'll find its functions in  the Library menu.

Alternatively you could simply try using built-in RS232 functions.

Or you may actually need to call that specific dll, in which case please add some detail more.

[Gaus]

If you have Visual Studio, you can use dumpbin to check if your required function is exported by the DLL.

dumpbin /exports filname.dll

[rolfk]

Who created that "useful" DLL?

With what compiler and version?

Was it compiled as release version?

With C Runtime library as external dependency or compiled into the DLL?