Rule creation

Hello, I need help on this rule:

CREATE RULE rule AS ON INSERT TO table WHERE (sum(new."field") > 10) DO
INSTEAD NOTHING;
Creation is ok but in inserting a row I get the following from pgaccessII
number -2147467259
ERROR: fireRIRrules: failed to remove aggs from qual...
Removing the INSTEAD from the rule inhibits the error but makes the rule
pointless as the statement execution proceeds to the insertion.
I need a rule that denies insertions if the total of the rows with an active
attribute maxes out (guess what, a vacancy set).
I'm confused, any help?

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