Problem with referential constraint

Hello, 

I was running into this problem earlier, but now I need an explanation,
cause it's important for project. Earlier I only deleted the referential
constraint. 
My tables are defined:
CREATE TABLE "TBL_RUECKMELDUNG"
(
	"LFD_RUECKFRAGENUMMER"               Integer    NOT NULL    DEFAULT
SERIAL (1),
	"RUECKMELDEDATUM"               Timestamp    DEFAULT TIMESTAMP,
	"LFD_ANFRAGENUMMER"               Integer,
	.....
	PRIMARY KEY ("LFD_RUECKFRAGENUMMER"),
	FOREIGN KEY "REF_RUECK_STAFFEL"	("LFD_ANFRAGENUMMER") REFERENCES 
	"TBL_STAFFELRUECKM" ("LFD_STAFFELNR") ON DELETE  CASCADE
)

CREATE TABLE "TBL_STAFFELRUECKM"
(
	"LFD_RUECKFRAGENUMMER"               Integer    NOT NULL,
            .....
	"LFD_STAFFELNR"               Fixed (10,0)    NOT NULL    DEFAULT
SERIAL (1),
	PRIMARY KEY ("LFD_STAFFELNR")
)


If I try to insert a new line into TBL_RUECKMELDUNG (through SQL-Studio
(latest Version)) I get an integrity constraint violation. If I insert a new
line into TBL_STAFFELRUECKM it works. 
My intention is:
TBL_RUECKMELDUNG contains one line and TBL_STAFFELRUECKM contains one or
more lines which are "linked" to the one line in TBL_RUECKMELDUNG. If I
delete this one line in TBL_RUECKMELDUNG I want to delete the "linked" lines
in TBL_STAFFELRUECKM
So I made the constraint TBL_RUECKMELDUNG -> TBL_STAFFELRUECKM. But after my
experience from below it seems that I have to make a constraint
TBL_STAFFELRUECKM -> TBL_RUECKMELDUNG. Is this right?
I have to fill my first table first, since it contains the main data and the
second one contains more 'detailed' data or maybe no data for that record in
TBL_RUECKMELDUNG.

I ran into the same problem (integrity constraint violation), as I tried to
execute the whole creation script of the database from the docs, which is
archived under
http://listserv.sap.com/pipermail/sapdb.general/2000-November/022897.html

I nearly forgot: I'm using a Redhat 9 box with SAPDB 7.4.3.25

Thanks in advance
Peter