[Rd] error location

[Peter Stencel]

Dear all,

I've written a (quite long) function in R. While running it I get the
following error message: 

 Error in "[<-"(`*tmp*`, 1, 13, value =
NULL) :
        number of items to replace is not a multiple of
replacement length
   operation failed in: function ()  !!!
   evaluation not successful!!!

How to interpret this error message? (There aren't any expressions that
I'm using in my function.) 

How can I locate the error? Is it possible to do it with the command
debug("functionname")? 

I'm new to R and I hope that someone can give me a piece of advice on
finding errors. Thanks in advance.

Regards, 
Peter