Check the package name is correct.
Yum is trying to find a package called "tclthread" and, indeed, there is no such package ... could it be you want something like:
yum install tcl tcl-devel
??
Apologies for replying first in English, my French is terrible - observe:
Vérifiez le nom de package est correct.
Yum essaye de trouver un package appelé le "tclthread" et, en effet, il n'y a aucun un tel package ... pourrait il être vous veulent quelque chose comme :
yum install tcl tcl-devel
Fortunately for me, the official language of LQ is English