Joins And Queries

Hi,

I have 3 tables.

From table 1, I join fields A, B, and C to fields A, B, and C on table 2. From Table 2, I join Fields 1 and 2 to Table 3. All the joins are Join 1.

When I pulled (Queried) fields D, E, and F from Table 1, field D from Table 2, and field D from table 3, I have a sum of $1000 under field (column) E from Table 1.

The second time I pulled data, I added fields A and B from table 1 to the query. However, I get a total of $1500 from the same column. i.e Field E from Table 1. I can understand that there will be more rows to provide further data breakdown, but I could not understnad why the total change.

Please help.

Thanks.