Problem with Visible property

Hello,

I'm currently trying to make a C script in order to load several values in a view window when it's openend and to save the same values when it's closed.
To detect the status of the view window, i used the following script:
Etat_fenetre=GetVisible("synop_RECETTE.pdl","Fenêtredevue1"); //Return-Type:BOOL
When it's opened for the first time, that works perfectly.
As it's closed, i get the following message error in Globalscript:
===================================OnErrorExecute====================================
SystemTime: (ThreadId 2592) 2006-03-09 23:44:58.484
dwErrorCode1: (ThreadId 2592) 1007007
dwErrorCode2: (ThreadId 2592) 1
szErrorText: (ThreadId 2592) PDLRTAPI oder DMAPI
szErrorTextInfo: (ThreadId 2592) Error in PDLRTSetProp
szApplicationName: (ThreadId 2592) PDLRuntimeSystem
bCycle: (ThreadId 2592) acycle
szFunctionName: (ThreadId 2592) @5e
lpszPictureName: (ThreadId 2592) SYNOP_RECETTE
lpszObjectName: (ThreadId 2592) Fenêtredevue1
lpszPropertyName: (ThreadId 2592) Visible
dwParamSize: (ThreadId 2592) 16
szErrortext: (ThreadId 2592) WinCC Runtime: PDL Runtime : Propriété introuvable

====================================OnErrorExecute====================================

And when i try to reopen my view window, the script detects it at closed, i.e. my values are saved and not loaded.

I obtained the same result with:
Etat_fenetre=GetPropBOOL(lpszPictureName,lpszObjectName,"Visible"); //Return-Type: BOOL

Is it a bug or perhaps have I made a mistake ?

Thanks

Kramps