I don't know what you are actually doing in the function calls of the DLL.
But you say you are getting timeouts. Who is the originator of the timeouts? Your DLL code or your LabVIEW code? If it is the DLL code -> your DLL functions were called.
If not, verify if your DLL functions are called by LabVIEW (even the application), please insert a MessageBox() in the DLL function call that executes first.
I expect that you executed the application on the same computer as you are developing in LabVIEW, is it? If not, you might be in "DLL hell".
If all of this does not help: Can you give any further details what you DLL code is doing?
Regards, Guenter