Boby Bianco beans

Of the 10 Boby Bianco sown only three came up and one of those does not look good. So I sowed another 6 today in toilet rolls again. The 7 which did not come up had rotted. Why? Too wet? Too cold? 9/10 Hestia and 6/6 Meraviglia di Venezia came up in the same conditions. Those appear to be doing well now, hardening off outside in the daytime.