Prior distribution for measurement errors


I am trying to set a small suport for uniform prior distribution. However, when I set a small support such as:

stderr gi_obs, uniform_pdf,0,0.01;

I got the following:

[code]??? Error using ==> chol
Matrix must be positive definite.

Error in ==> metropolis_hastings_initialization at 52
d = chol(vv);

Error in ==> random_walk_metropolis_hastings at 58
ix2, ilogpo2, ModelName, MhDirectoryName, fblck, fline, npar,
nblck, nruns, NewFile, MAX_nruns, d ] = …

Error in ==> dynare_estimation_1 at 871

Error in ==> dynare_estimation at 62

Error in ==> new_formulation at 451

Error in ==> dynare at 132
evalin(‘base’,fname) ;

On the other hand, if I set a support such as:
stderr gi_obs, uniform_pdf,0,0.1;

The estimation works fine. As far as I remember, the support for the uniform distribution, U[a,b], should work with any number from -inf<a,b<inf .

Am I missing something? Thanks