In your case, the situation is as follows:
You want to analyze a column for which the result is displayed as a currency (floating).
In your example, the SQL query returns one value 12000 and three NULL values.
Although you see empty cells, in fact, the table internally substitutes 0 (zero). Therefore, your analysis on an empty cell will not give a result.
There can be two ways out:
1. Use the property .Cell[1, i].Empty = True for analysis in your example.
2. Create a calculated field that will output 0 instead of ZERO and then parse .Cell[1, i].AsFloat = 0 in your example.

i used a script but it shows an error