Crypto failes on Windows Mobile 5

The below code was working fine on PPC2000, 2002 and 2003 versions but
stopped working with Windows Mobile 5. I get CryptAcquireContext Failed
Exception.

Relevant sections of the code are below.

***
Private Const CryptDll As String = "coredll.dll"


<DllImport(CryptDll)> _
Public Shared Function CryptAcquireContext( _
ByRef phProv As IntPtr, ByVal pszContainer As String, _
ByVal pszProvider As String, ByVal dwProvType As Integer, _
ByVal dwFlags As Integer) As Boolean
End Function

***

If Not WinApi.CryptAcquireContext(hProv, Nothing, WinApi.MS_DEF_PROV,
WinApi.PROV_RSA_FULL, WinApi.CRYPT_VERIFYCONTEXT) Then
Failed("CryptAcquireContext")
End If

***

Thanks for any help or insight someone can provide
DPC