One of Smart's weaknesses is the inability to properly reconcile bi-arch packages, and I've heard of cases where it's pulled in i586 packages when unable to find x86_64. Yast/zypper is much better in this manner.

Having said that, keep in mind that the 64-bit package list also includes 32-bit compatibility packages with the indicator -32-bit as part of the package name; if they were truly 32-bit they'd be listed as i386/i586/i686.

Sometimes when the build-service is building new packages, you wind up in a bit of a limbo stage where dependent packages aren't actually available, and this can throw up errors similar to the one you're receiving, though without knowing the actual message, that's a guess. Could be that if you try again within a few hours after the mirrors have updated, it may resolve itself.

But the other thing I really didn't like about Smart was that I found it too frequently wanted to downgrade/uninstall packages when it couldn't resolve dependencies, rather than manually stepping through them via Yast. So that's just a subtle suggestion to maybe try Yast, too. It could actually help you narrow down where the problem may be.

Anyways, just my 2c...

Cheers,
KV