Delphi - ADO query and FillChar generates errors

Question

I have the following code:

var wqry:TAdoQuery;
...
  FillChar(wSpaces,cSpacesAfter,' ');
  try
    wqry := TADOQuery.Create(nil);//here the error
    wqry.Connection:=...

cSpacesAfter is a constant and has the value 1035. wSpaces is a local string variable. The problem is that I receive the following error when TAdoQuery is created

even it is in french, I believe you got the idea.....

If I comment the FillChar code, everything works ok. I have the usual compiler directives, nothing special. I'm using Delphi 7.

Can someone tell me what is wrong with that code?