Well I'll answer myself because I found a solution but I still don't know why it works.
After adding another case, I compile the main.prg program and then build the dll. This way I don't get the error and life is once again great.
What is mind boggeling is that I have the recompile all files checkbox checked when I build the dll so I can't understand why compiling the main.prg program should make a difference.

So if someone could reply to this thread and let me know what is going on that would be great.

Einar

>I can reproduce this error every time I try this.
>Add the following code:
>

>CASE oProp.Action == 'einar'
>	lcHTMLfile = 'einar.htm'
>	lcHTMLout= FILETOSTR(oProp.HtmlPath+lcHTMLfile)
>	lcHTMLout= oHTML.mergetext(lcHTMLout)
>

>to the top of the case statement in the main() function in main.prg.
>The try to build the dll. It goes through the building process and it accually creates the dll (changes the time stam anyways), but then I receive the following error:
>

>Function argument value, type or count is invalid.
>

>
>What am I doing wrong? Can anyone explain this?
>
>Einar