I'm moving my server from from OES 11 SP1 (SLES 11 SP2) to OES 11 SP2 via SMT, but when I run zypper upgrade -t patch I've a dependencies errors:

# zypper update -t patch
Loading repository data...
Reading installed packages...
Resolving package dependencies...
2 Problems:
Problem: libzypp-9.40.2-14.7.x86_64 requires libz.so.1(ZLIB_1.2.3.3)(64bit), but this requirement cannot be provided
Problem: yast2-qt-pkg-2.21.4-2.5.56.x86_64 requires libzypp.so.908()(64bit), but this requirement cannot be provided

Problem: libzypp-9.40.2-14.7.x86_64 requires libz.so.1(ZLIB_1.2.3.3)(64bit), but this requirement cannot be provided
uninstallable providers: zlib-1.2.7-0.10.128.x86_64[SMT-http_smtsles_apa_it:SLES11-SP3-Pool]
zlib-1.2.7-0.12.3.x86_64[SMT-http_smtsles_apa_it:SLES11-SP3-Updates]
Solution 1: Following actions will be done:
deinstallation of libzypp-9.16.4-0.5.2.x86_64
deinstallation of smt-client-0.3.0-0.5.1.x86_64
deinstallation of yast2-pkg-bindings-2.17.61-0.7.2.x86_64
deinstallation of yast2-ncurses-pkg-2.17.20-0.5.1.x86_64
deinstallation of PackageKit-0.3.14-2.30.11.x86_64
.......
.......
deinstallation of novell-plugin-base-2.7.6-0.12.25.1.noarch
deinstallation of novell-plugin-nss-3.6.624-0.3.1.x86_64
Solution 2: deinstallation of zlib-devel-1.2.3-15.2.x86_64
Solution 3: do not install patch:slessp3-softwaremgmt-201505-2-10699.noarch
Solution 4: break libzypp-9.40.2-14.7.x86_64 by ignoring some of its dependencies

Can I ignore dependencies (solution 4)?
Does I need zlib-devel ?
How to move?

Thanks for help,
Fabrizio