Provider Cannot Be Found. It May Not Be Properly Installed.

i do not understand.
I have this code:
#import "C:Program FilesCommon FilesSystemADOmsado15.dll" no_namespace rename("EOF", "EndOfFile")
...
_ConnectionPtr Conn;
...
CoInitialize(NULL);
HRESULT hr = Conn.CreateInstance(__uuidof(Connection));
Conn->Provider = "Microsoft.Jet.OLEDB.4.0";
Conn->ConnectionString="Data Source=c:\mydb.mdb;";
hr = Conn->Open( "","Admin","", adConnectUnspecified);
Whith My account this code work good, but when i try to start my program whith another user login, i have this error:
hr=0x800a0e7a -> Provider cannot be found. It may not be properly installed.
Why by my login program run normal, but by another login failed? OS Xpsp2 whith standart MDAC 2.8 installed.