Need help grouping with on substr

[Inpresif]

I have this data in my table:
CODE PRICE
slp_1 EUR 54.95
pvl_1 EUR 64.95
pvl_4 EUR 189.95
int_1 EUR 64.95

I want to group it using a substr function, so I can calculate total sales per 'code', like this:
SELECT sum(PRICE) AS Total,substr(USR_PRODID, 0, 2) AS Prod FROM sales_tbl GROUP BY substr(CODE, 0, 2);

It should result in this:
Prod Total
slp 54.95
pvl 254.90
int 64.95

It's not working:/

Anybody having a clue what I can/should do?

[Inpresif]

I found a fix after a lot of searching, this does actually work, not sure if there's a way with substr though?

SELECT sum(prijs) AS Total, left(CODE, 3) AS Site FROM sales_tbl GROUP BY left(CODE, 3)

[Thora_Fan]

What exactly is it not doing? Are you receiving an error or is it just not returning results?