[stunnel-users] Problem Selecting Only Ecliptic Curve Ciphers

I'm using stunnel 4.56 on Windows 7. When I use the following cipher list:

ciphers = ECDHE-ECDSA-AES256-SHA:ECDH-ECDSA-AES256-SHA:ECDHE-ECDSA-AES128-SHA:ECDH-ECDSA-AES128-SHA

to establish a connection, I get a "no shared cipher" response.

The following set of ciphers does work:

ciphers = ECDHE-RSA-AES256-SHA:ECDHE-ECDSA-AES256-SHA:ECDH-RSA-AES256-SHA:ECDH-ECDSA-AES256-SHA:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES128-SHA:ECDH-RSA-AES128-SHA:ECDH-ECDSA-AES128-SHA

Other relevant settings:

options = NO_SSLv2 sslVersion = all fips = no verify = 2

If I take out the first ECDHE-RSA-ASE256-SHA cipher from the list, the ECDHE-RSA-AES128-SHA cipher is selected.

What am I doing wrong?

Thanks.