Com Error - Class Not Registered

[gruntydatsun 12]

I have an odd problem so here goes.

I have a 32bit DLL that is used to generate a number based on a supplied string and number.

The code to use the DLL file is below:
 

Local $oErrorHandler = ObjEvent("AutoIt.Error", "_ErrFunc")
Local $oAMS = ObjCreate("AMSR.GenStr")
Local $sOutput = $oAMS.GenerateString(GuiCtrlRead($cmb_App),GUICtrlRead($input_ID),"useless string goes here")

Func _ErrFunc($oError)
    ; Do anything here.
    MsgBox(0,"COM ERROR: AMMS Registration Tool v1.0","Error Number: " & @TAB & "0x" & Hex($oError.number) & @CRLF & _
            "Help Context: " & @TAB & $oError.helpcontext & @CRLF & _
            "Last DLL Error: " & @TAB & $oError.lastdllerror & @CRLF & _
            "Line Number: " & @TAB & $oError.scriptline & @CRLF & _
            "Return Code: " & @TAB & "0x" & Hex($oError.retcode) & @CRLF & _
            "Description:" & @TAB & $oError.windescription)
EndFunc

OK, so I can register the required DLL on a 32 bit WIndows XP OS, compile it the Autoit above to (EXE1) and then run it successfully. No problem.

If I take EXE1 onto a Win7-64 machine, register the 32bit DLL using regsvr32 from SysWOW64 then EXE1, runs no problems.

If I compile exactly the same code on the Win7-64 machine as either 32bit or 64bit (EXE2) it fails to run with Description "Class Not Registered".

Any help greatly appreciated.  It's got me stumped.