Hi Leo,

>The value of 'lcLevNr' string variable contains a cow's registration number (e.g. "NL 111111110"). I looked up the specifications and saw there is no reason to pass it by reference. It's maybe better then to pass it by value?
>I already tried to pass the 'lcLevNr' string variable by value, (I allso modified the declare commands to: "STRING tcCow"), but it makes no difference.

I wasn't sure if this variable was input or output parameter. So far I don't see anything wrong with your code. I'm pretty sure that problem is with DLL you're using. It's strange that it relies on the memory reserved by calling program instead of allocating as much memory as it required. You certanly don't have any control over how VFP manage it's memory.

>By the way: sorry if my English 'sounds stupid sometimes'
>I'm not a grown up englisch talker :-)

Your English is quite good. I'm not "englisch talker' eaither. :)