Comment 19 for bug 910143

I also had this issue with 64-bit Precise.
The nlpsolver extension showed up in the extensions list within Libreoffice, but I was unable to enable it.

All that was required for me to resolve this was to run: $ sudo apt-get install libreoffice
13 addinional packages were installed (listed below) and I was then able to enable the solver extension from within Libreoffice.

fonts-sil-gentium
fonts-sil-gentium-basic
libservlet2.5-java
libhsqldb-java
libxml-commons-resolver1.1-java
libxml-commons-external-java
libxerces2-java
libreoffice-java-common
libreoffice-base
ttf-dejavu
ttf-sil-gentium-basic
libreoffice-filter-mobiledev
libreoffice