DLL problem with .net

I’m really new to both Powerbasic and DLLs
So what I need is to make a DLL that I can use in both Visual Basic 2008 and Powerbasic 9

What I’ve done so far is to use the standard DLL framework in PB9
Added a skeleton for my program and compiled it to a DLL.

In VB9 when I tried to run it says
"A first chance exception of type 'System.EntryPointNotFoundException' occurred in testDll.exe"

powerbasic code as follows
------------------------------------------------------------------

#COMPILE DLL
#DIM ALL
%USEMACROS = 1
#INCLUDE "Win32API.inc"
GLOBAL ghInstance AS DWORD
'-------------------------------------------------------------------------------
' Main DLL entry point called by Windows...
'
FUNCTION LIBMAIN (BYVAL hInstance AS LONG, _
BYVAL fwdReason AS LONG, _
BYVAL lpvReserved AS LONG) AS LONG
SELECT CASE fwdReason
CASE %DLL_PROCESS_ATTACH
'Indicates that the DLL is being loaded by another process (a DLL
'or EXE is loading the DLL). DLLs can use this opportunity to
'initialize any instance or global data, such as arrays.
ghInstance = hInstance
FUNCTION = 1 'success!
'FUNCTION = 0 'failure! This will prevent the EXE from running.
CASE %DLL_PROCESS_DETACH
'Indicates that the DLL is being unloaded or detached from the
'calling application. DLLs can take this opportunity to clean
'up all resources for all threads attached and known to the DLL.
FUNCTION = 1 'success!
'FUNCTION = 0 'failure!
CASE %DLL_THREAD_ATTACH
'Indicates that the DLL is being loaded by a new thread in the
'calling application. DLLs can use this opportunity to
'initialize any thread local storage (TLS).
FUNCTION = 1 'success!
'FUNCTION = 0 'failure!
CASE %DLL_THREAD_DETACH
'Indicates that the thread is exiting cleanly. If the DLL has
'allocated any thread local storage, it should be released.
FUNCTION = 1 'success!
'FUNCTION = 0 'failure!
END SELECT
END FUNCTION
FUNCTION CalculatePrice(Designation AS STRING, Amount AS INTEGER, Discount AS DOUBLE) EXPORT AS STRING

SELECT CASE LEFT$(Designation,1)
CASE "H", "F", "P", "R", "T", "Z", "C"
CalculatePrice = Designation
CASE "M", "K"
CASE "L"
CASE "W"
CASE "B"
CASE "A", "S", "D"
END SELECT

END FUNCTION

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