problem to save workspace

Hi,

I have a problem to save my workspace when I change the variables names.

Look:

Save workspace image? [y/n/c]: y
Warning messages: 
1: namespaces may not be available when loading 
2: names in persistent strings are currently ignored 

When I reload R:
I get the error:

Error in get(x, envir, mode, inherits) : variable "biplot" was not found
Fatal error: unable to restore saved data in .RData

Thanks
Ronaldo
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Insecta - Entomologia
Departamento de Biologia Animal
Universidade Federal de Vi?osa