Problem with DirectFunctionCall3(array_in,...)

Hi!

At the moment I'm trying to create an own datatype "timeseries", which should contain among others an array of float8 values.

As far as I know, float8 is a base type of postgres and therefore I shouldn't need to create an own array-type.

In my own C-function "timeseries_in()" I would like to use "array_in()" implemented in arrayfuncs.c. To insert a timestamp with timezone, I'm using

DirectFunctionCall3(timestamptz_in, CStringGetDatum(zeitstempel), ObjectIdGetDatum(InvalidOid), Int32GetDatum(-1));

and it works fine... Trying the same with

DirectFunctionCall3(array_in, CStringGetDatum(arraystring), ObjectIdGetDatum(20), Int32GetDatum(-1));

unfortunately smashes my postmaster...

Having done a lot of research, I can't spot the mistake. Does anyone know the problem or have a workaround for me?

Please tell me, if you want me to supply my source code or anything else...

MfG
Jessica