error in running optimx

Hello,I tried installing optimx and got a confirmation that it was installed. However, anytime I call for it, I received the following error message

library("optimx", lib.loc="~/R/win-library/3.1")Error in loadNamespace(j <- i[[1L]], c(lib.loc, .libPaths()), versionCheck = vI[[j]]) :?? there is no package called ?quadprog?In addition: Warning message:package ?optimx? was built under R version 3.1.3?Error: package or namespace load failed for ?optimx?

When I go ahead to run my code, I have the following error message:
Error: could not find function "optimx"

How do I go about solving this issue.
Thanks.Olufemi
?