How to calculate the weighted average of data joining two tables and by grouping two columns

Question

I'm trying to composite assay geology data, this must be done by each lithology from drill-hole, so I have two tables assay and geology.
In assay table I have hole number, From, To and P2O5, and in the geology table I have hole number, Ore Zone.

I select hole number, ore zone from the geology and calculate the average weight with assay P2O5, From and To (difference will give me the length) columns.

SELECT
    UDEF_GEOLOGY.HOLE_NUMBER,
    UDEF_GEOLOGY.ore_zone,
    MIN(UDEF_GEOLOGY.depth_from) AS 'From',
    MAX(UDEF_GEOLOGY.depth_to) AS 'To',
    SUM(CAST(HOLE_ASSAY_SAMPLE.P2O5_per_MEXRF26K AS FLOAT)* CAST((HOLE_ASSAY_SAMPLE.depth_to-HOLE_ASSAY_SAMPLE.depth_from) AS FLOAT))/ SUM(CAST((HOLE_ASSAY_SAMPLE.depth_to-HOLE_ASSAY_SAMPLE.depth_from) AS FLOAT)) AS 'P2O5_POND'
FROM
    udef_geology
INNER JOIN HOLE_ASSAY_SAMPLE ON
    UDEF_GEOLOGY.HOLE_NUMBER = HOLE_ASSAY_SAMPLE.HOLE_NUMBER
GROUP BY
    UDEF_GEOLOGY.HOLE_NUMBER,
    UDEF_GEOLOGY.ore_zone
ORDER BY
    UDEF_GEOLOGY.HOLE_NUMBER,
    MIN(UDEF_GEOLOGY.DEPTH_FROM)

I expect to get the pound result for each ore zone and hole number instead this sentence gives me the pound of all hole numbers.