>Set objMy = New acode1
>Set r = objMy.calcplanets("12/23/1997", "12:15", 89.03, 6, 42.41, "W", _
> "JUP", 4, hlon, hlat, Rv, Glon, GLat, Dearth, ra, dec, asize, elong, phs, mag, False)

I think you can use the same function call. Each parameter which changes value in the function should have the 'at' sign on the front (@).

You need to declare the function with all the parameters - look at the DECLARE - DLL help. I think it goes something like this (most of my dll functions are in classes so I don't look at them much):-

DECLARE (return_value_type) calcplanets IN (libraryname)
STRING cDate,
STRING cTime,
DOUBLE xxx,
INTEGER yyy,
INTEGER @return_integer,
STRING @return_string,
INTEGER @return_string_length,
etc.

You need to make sure the upper & lower case of the function name is exact. Also initialise all the variables before actually calling the function.
Hope this helps,