Macro encryption different in between 4.2 and 5.1

A extension made with password protected Basic Libraries using LO 5.1  
do not "load" properly the libraries under LO 4.2

We load a  password protected library using the folowing code.
If (Not GlobalScope.BasicLibraries.isLibraryLoaded("DbUtils")) Then
GlobalScope.BasicLibraries.LoadLibrary("DbUtils")
End If
extension Build and used in 4.2  makes all functions and sub's available 
in memory.
extension Build and used in 5.1  makes all functions and sub's available 
in memory.
extension Build in 4.2 and used in 5.1: the functions and Sub's in the 
libraries are not available,  its only after opening the library  
"manualy" and after entering the password that make the functions and 
the sub's available in memory.

The extensions are build under Windows
There is a difference in size between the extension build in 5.1 and 4.2
5.1 gives 69 KB
4.2 gives 67 KB
There is no error after "GlobalScope.BasicLibraries.LoadLibrary("DbUtils")
once the librarie is opened with the password, then 
"GlobalScope.BasicLibraries.LoadLibrary("DbUtils")"  is working fine 
even after closing LO !!!!!!

Can someone confirm this behavior and sould i filled a issue ?

Thanks

Fernand