I will post here the O9001 subprogram i loaded, maybe it will help.
I notice that it ends with M99 which will force the controller to begin the main program?
%
O9001
#3003=1
#3004=1
IF[#4120EQ0]GOTO99
IF[#500EQ#4120]GOTO99
G91G28Z0
G91G30Z0
M19
M55
M56
G4X0.5
G91G28Z0
T#4120
M57
G91G30Z0
M58
G4X0.5
M59
N99#500=#4120
#3003=0
#3004=0
M99