If I put the sum(Field01) function in a calculation field the result is.... Field01 of 1st Record + Field01 of 2nd Record + Field01 of N Record.

My problem is that i don't want to sum all the records,

A summary field may be what you need but I am afraid that you have not supplied enough information as to what are you trying to achieve.

Your premise is incorrect. It would be correct if you were referencing a RELATED field - then the result would be:

Field01 of 1st Related Record + Field01 of 2nd Related Record + ... + Field01 of Nth Related Record

Now, what DO you want to sum?

I have 2 tables that are related with a "year" field . One table is the "invoices" and the other is the "MonthBalance). In the second table i have 12 fields (TotBalane Jan,TotBalane Feb,TotBalane Mar.....TotBalane Dec). So I want to sum the total balance of all the invoices of 2006(example) but i want the field "Totalbalance Jan" to appear the total balance of the invoices that where created in Jan 2006.

I hope now understand my problem :

sorry for my English

The way you have it now, you would need 12 separate relationships between the tables.

A simpler solution would be to have 12 RECORDS in the MonthBalance table.

Even simpler would be to produce a report in Invoices, sub-summarized by month.