FTDI, function FT_Write returning FT_INVALID_HANDLE

After hours of failed attempts i ask your help  once more

I'm writin a simple GUI  interface ,working under Windows XP, to communicate 
with some existing boards mounting  FTDI FT232RQ.

At first i used the Virtual COM VCP drivers 2.08.14 ,everything worked 
fine,but now i need to use the FTD2XX.dll functions.

Many function were working OK,as 
FT_ListDevices,FT_Open,FT_SetBaudRate,FT_SetDataCharacteristics.

I have problems with FT_Write returning FT_INVALID_HANDLE,i call it just 
after verified that FT_Open returns FT_OK.

Can you explain the reason of such an error?Does it depend from previous 
installations of VCP drivers?

Many thanks
Diego 

Diego: I have the same problem. �Did you solve it?�How?

Thanks

Federico

El mi�rcoles, 18 de enero de 2012 08:43:44 UTC-2, blisca  escribi�:
> After hours of failed attempts i ask your help  once more
> 
> 
> 
> I'm writin a simple GUI  interface ,working under Windows XP, to communicate 
> 
> with some existing boards mounting  FTDI FT232RQ.
> 
> 
> 
> At first i used the Virtual COM VCP drivers 2.08.14 ,everything worked 
> 
> fine,but now i need to use the FTD2XX.dll functions.
> 
> 
> 
> Many function were working OK,as 
> 
> FT_ListDevices,FT_Open,FT_SetBaudRate,FT_SetDataCharacteristics.
> 
> 
> 
> I have problems with FT_Write returning FT_INVALID_HANDLE,i call it just 
> 
> after verified that FT_Open returns FT_OK.
> 
> 
> 
> Can you explain the reason of such an error?Does it depend from previous 
> 
> installations of VCP drivers?
> 
> 
> 
> Many thanks
> 
> Diego