Solaris machines have a unique set of problems with GPT installations. In general most of the problems with Sun platforms can be solved by installing additional GNU packages from the sun freeware site. Here are some particulars:
Solaris ships with a perl executable that is built with Sun's vendor compiler. Some of the modules that GPT uses are designed as plugins to the perl executable and so need to be compiled with the tools that perl itself was built with. Unfortunately out-of-the-box Solaris machines do not include the vendor compiler which means that these modules cannot be built. The solution is to either get the Sun vendor compiler or rebuild perl with GCC.
Solaris ships with a tar program that is not compatible with GNU tar. GNU tar is what GPT bundles and packages are created with. GPT attempts to detect GNU tar from your PATH but there are times when it may choose the wrong one. To make run gpt-config -list.