How can I install a toolbox on Mac?

i wanted to install some mathworks toolboxes (econometrics), additional to an already installed r2011a student version. the installation was done by a backup copy of a computer where I had matlab incl. toolboxes installed. matlab runs fine, but the toolboxes not.

after having downloaded the installation manager for installing the toolboxes again, when the installation application is asking for an installation folder, I get an error "unable to create folder...". the application is trying to create the already existing folder MATLAB_R2011a_Student. what can i do?

many thanks

[Aaron]

I have the exact same problem on Linux.