MQ must be manually installed in the global zone before installing Enterprise Server in a sparse local zone. There are two work-arounds for this issue:
Install MQ 4.1 manually in the global zone from the same media on which Enterprise Server 2.1 IFR installation is located to get the latest MQ packages.
Use the installer that corresponds to your platform:
mq4_1-installer-SunOS.zip mq4_1-installer-SunOS_X86.zip mq4_1-installer-Linux_X86.zip mq4_1-installer-WINNT.zip
Unzip the bits and run the installer.
The installer will be in the mq4_1-installer directory.
Install any component of IFR installation in global zone. This action would check the version of MQ in GZ and if required upgrade it to the one bundled in Enterprise Server 2.1 IFR. Even Selecting and Installing the Sample Applications component upgrades MQ to IFR version.
Run the Enterprise Server installation in the global zone, but select only the sample components.
The sample component installation also installs MQ and Enterprise Server shared components in all zones.
Run the Enterprise Server installation again, this time in the local sparse zone.
Installation should complete without any problems.