Spatio temporal anisotropy

Dear list
I'm working on monthly spatio-temporal data. After running emperical
spatiotemporal variogram and fitting purely spatial and temporal
variograms, i wanted to compute spatio-temporal anisotropy. When i run the
function estiStAni(empVgm,interval=spVgmMod$range), this Error will be
appear :
Error: variable 'dist' was fitted with type "numeric" but type "other" was
supplied

I do not know what is the problem.

Thanks alot for any help.