In my case, I accidentally created a S4-method and another normal function with the same name. The package could be installed. However, as I tried to load the package, it prints the following error message:
Loading required package: cycle Error in loadNamespace(package, c(which.lib.loc, lib.loc)) : cyclic namespace dependency detected when loading 'cycle', already loading 'cycle' It looks like this package has a loading problem: see the messages for details.
For a minimal piece of code see https://gist.github.com/anonymous/10018579. When the file is put in a R file in the R package, and in NAMESPACE "export(myMethod)" is specified, the checking or loading of the package will fail due to the "cyclic namespace dependency".
The error message is unfortunately not particularly helpful. Normally it would point to a problem of reciprocal dependency, but in this case it is only caused by a name that is given to both a S4 method and a normal function.
It is straightforward to solve the issue: check carefully whether you have duplicated function/method names and fix them if there are any.