Small_Baseline STAMPS error

Dear
I’m trying to run with STAMPS the small baseline but I have the problem in matlab

stamps

STAMPS: ########################################
STAMPS: ####### StaMPS/MTI Version 4.0b6 #######
STAMPS: ####### Beta version, Jun 2018 #######
STAMPS: ########################################

Reference to non-existent field ‘small_baseline_flag’.

Error in ps_parms_default (line 111)
if strcmpi(parms.small_baseline_flag,‘y’)

Error in getparm (line 14)
ps_parms_default

Error in stamps (line 69)
quick_est_gamma_flag=getparm(‘quick_est_gamma_flag’);

Someone could help me??

Thanks

Pedro