Texmaker and TeXstudio ⇒ Packages not installing

[mtanner]

I am using TexMaker 5.0.3 of Windows 7. When I add a new package to the preamble, for example
\usepackage{showlabels}

then the package appears to be downloaded, but when I compile my Latex document I get a message saying the .STY file cannot be found. This has happened across multiple packages. What is the problem and how do I fix it please?

[rais]

An answer to your question may depend on your (La)TeX distribution.
(personally, I do my package installations by calling tlmgr---the (La)TeX package manager for my distri, TeXlive)

KR
Rainer