as i see this code... look at your IF THEN statements

Code:
time:
                if time_pick < 13308 then time1	
	if time_pick < 26615 then time2
	if time_pick < 39722 then time3
	if time_pick < 52829 then time4

	time_pick = 1500 : return			                                        
time1:
	time_pick = 800 : return
RETURN statement are use with GOSUB. In this case theres no gosubs, so your program don't know where to return. simply modify as

Code:
                if time_pick < 13308 then GOSUB time1	
	if time_pick < 26615 then GOSUB time2
	if time_pick < 39722 then GOSUB time3
	if time_pick < 52829 then GOSUB time4
this is suppose to fix your problem

can also do

if time_pick<13308 then
time_pick=800
endif

maybe less jumping between here, there, somewhere will be more easy to debug.