Error ? Reference to non-existent field 'varobs'

Hi everybody,
I am dealing with a bayesian estimation on dynare 4 and Matlab 7.5 (on mac). I think that i have set everything right but i get the following error message when i run the .mod file.

??? Reference to non-existent field ‘varobs’

I make sure that my observable variables are in the same order in the excel file.
I will really appreciate any help to fix my problem.
Please help.

follicule