Canon 01 error message

[rockape2001]

I have a Canon 500d - have bought 2 Sigma lenses one an 500mm APO which has been chipped to f5.6 and should work on a DSLR - every now and again get error message 01 communication between camera and Lens failed clean contacts. I have googled the problem and seems to be a general fault on early Sigma lenses - apart fro cleaning contacts has anyone solved the problem

[cosmicma]

dunno if you've sorted this out yet but it sounds to me as if it hasn't been re chipped hence the comunication error

i have an old sigma 105mm f2.8 macro lens that will only work at f2.8 on both a 40d and 50d try to close the apeture and i get the same error
the error also pops up every now and again even at f2.8 and i know the lens hasn't been re chipped