Can't update decimal field in mssql

When I execute this query:

UPDATE test_temp SET

test_temp.aut_z3 = 2.99, 
test_temp.slo_z3 = 0, 
test_temp.ita_z3 = 0

WHERE test_temp.product_id_part_1 = 10877
    AND test_temp.product_id_part_2 = 0 

using SSMS it works. But if I try to do the same in C# using Dapper then noting happens.

It won't update the test_temp.aut_z3 field.

C# code:

var sqlStatement = @"
UPDATE test_temp SET

test_temp.aut_z3 = 2.99, 
test_temp.slo_z3 = 0, 
test_temp.ita_z3 = 0

WHERE test_temp.product_id_part_1 = 10877
    AND test_temp.product_id_part_2 = 0 

";

await sqlConnection.ExecuteAsync(sqlStatement, null, null, DapperHelper.CommandTimeout);

I have also tried it like this, but the result is the same. Nothing happens:

var sqlStatement = @"
UPDATE test_temp SET

test_temp.aut_z3 = @aut_z3, 
test_temp.slo_z3 = @slo_z3, 
test_temp.ita_z3 = @ita_z3

WHERE test_temp.product_id_part_1 = @product_id_part_1
AND test_temp.product_id_part_2 = @product_id_part_2 

";

var sqlParameters = new
{
product_id_part_1 = 10877,
product_id_part_2 = 0,
aut_z3 = 2.99,
slo_z3 = 0,
ita_z3 = 0
};

await sqlConnection.ExecuteAsync(sqlStatement, sqlParameters, null, DapperHelper.CommandTimeout);

Any idea why?