Quick - debugging "Data expression error"

[EDISR@detroitedison.com]

G'day 
 
These errors usually are due to either bad data or not understanding the
range 
of data you are processing.  I agree that one way is to copy suspected code
to 
QTP or QUIZ and test it but first you have to narrow down the data set that
is 
most likely causing the error.  I have usually solved the problem by
creating 
a copy of the screen in a simplified form (i.e. not procedures, lookups
etc.) 
and then add components one by one.  It usually turns out to be a lookup 
(REFERENCE) as the culprit! 
 
Even more serious is when you get FORCED EXITS!  Beware of reading a table 
where the key may contain a NULL or performing date conversions and 
comparisons with a NULL date. 
 
Blue in Michigan 
 
OpenVMS 5.5-2, PH 6.10e, ORACLE Rdb 4.1