Stored Proc works intermittently

Hi All.

We have tried to create a stored proc to block users from adding an invoice if the GP % is not within a certain range (this is defined in UDF's) for certain bp's.

However does not work for all values within the range.

example. customer A's GP % should be between 5 and 30%

it will let an invoice with 16% go through, but will block a document with a 24% GP.

Please see the code below which we have used.

begin error := 0;

error_message := N'Ok';

IF :object_type = '13'AND :transaction_type = 'A'THEN

SELECT

(SELECTCount(*)

            FROM OINV T0 INNERJOIN INV1 T1 ON T0."DocEntry" = T1."DocEntry"

            INNERJOIN OCRD T2 ON T0."CardCode" = T2."CardCode"

            WHERE T0."DocEntry" = :list_of_cols_val_tab_del

            GROUPBY T1."DocEntry", T0."DocEntry", T0."DocTotal", T0."VatSum",T2."U_MinMargin",T2."U_MaxMargin"

            HAVINGnullif(T0."DocTotal" - T0."VatSum" - (SUM(T1."Quantity" * T1."GrossBuyPr")), 0)/ nullif(SUM(T1."Quantity" * T1."GrossBuyPr"), 0) * 100 notBETWEEN"U_MinMargin"and"U_MaxMargin"

            ) into temp_var_1 FROM DUMMY;

    IF :temp_var_1 > 0 THEN

        SELECT -1, 'ERROR: Check GP%'INTO error, error_message FROM DUMMY;

    ENDIF;

ENDIF;

We have used the NOT BETWEEN and

HAVINGnullif(T0."DocTotal" - T0."VatSum" - (SUM(T1."Quantity" * T1."GrossBuyPr")), 0)/ nullif(SUM(T1."Quantity" * T1."GrossBuyPr"), 0) * 100 >="U_MinMargin" or (T0."DocTotal" - T0."VatSum" - (SUM(T1."Quantity" * T1."GrossBuyPr")), 0)/ nullif(SUM(T1."Quantity" * T1."GrossBuyPr"), 0) * 100 >="U_MaxMargin"

and get the same behaviour..any GP% that is in the twenties gets blocked

Any ideas on what it could be.

Thank you

Jerusha