error: found '{' at file scope (missing function header?)

[Angelika Kratochwil]

hello!
i got following error while building bison: found '{' at file scope 
(missing function header?)

do you know what it could be? the problem is that i have an other 
development environment, but i'm using the same bison version, 2.1. 

I don't changed anything in my bison code. do you know more about that 
error? I don't know what to do, because its while generating the c file of 
the bison.y file. 

best regards
angelika