upper value using MINOS

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What steps will reproduce the problem?
1. Trying to use MIGRAD and MINOS to find errors on a non-linear function.
2.
3.

What is the expected output? What do you see instead?

I expect to see amples (NEW API)correct parameter errors.  The parameters seem 
to fit well but the errors with just MIGRAD or HESSE seem too small.

When I run MINOS I get outputs that say:

negative or zero diagonal element 0 in covariance matrix
negative or zero diagonal element 1 in covariance matrix
MnMinos could not find upper value for parameter 1


I am not really sure what this means or what I could do to fix it. Any help or 
explanation would be nice, Thank you!

What version of the product are you using? On what operating system?

I am using the newest version of pyminuit

Original issue reported on code.google.com by kcremin%[email protected] on 8 Aug 2011 at 5:48