R help - Mar 2005 - help on warning message when using anova

Hi can someone help me with the following warning message I got when I used two
way anova: Warning messages: 1: Models with response "NULL" removed
because
response differs from model 1 in: anova.lmlist(object, ...) 2: Models with
response "NULL" removed because response differs from model 1 in:
anova.lmlist(object, ...)
 (I have two rows of separate data sets)

Thanks in advance,

tao