I have the solution after a lot of work.
Using Windows 10
1) Find the msstdfmt.dll in windows (easy with the explorer) and copy it in sysWOW64.
2) CMD to get the DOS Windows. Type CD\. Then write regedt32 msstdfmt.dll
3) In the search line, find "Command Prompt" or "invite de commande" (for French PC) and click right mouse on the name found to run as an administrator (important step even if you are an administrator of the PC) 4) Then [ENTER] in the DOS window and the DLL will be recorded. 5) Follow the RC4 manual loading the FSX flight plan and no problem anymore Good flight
