I'm probably barking up the wrong tree on this, but here goes...

When you say "does not insert" do you mean that:
A. No new records are added in the FOR loop
or
B. Records are added, but the fields are blank.

Demo code --- only vaguely similar to what you'd posted:

SELECT 0
CREATE TABLE TableA FREE ( ;
    Col01   C(10), ;
    Col02   C(10), ;
    Col03   C(10), ;
    Col04   C(10) )
INSERT INTO TableA VALUES ("One","Two","Three","Four")

SELECT 0
CREATE TABLE TableB FREE ( ;
    Col01   C(10), ;
    Col02   C(10), ;
    Col03   C(10), ;
    Col04   C(10) )
INSERT INTO TableB VALUES ("Fee","Fie","Foe","Fum")

* Position the record pointer at EOF in TableA
GOTO BOTTOM IN TableB
SKIP IN TableB

SELECT TableA
? "Current table: ", ALIAS()
? "Col01 = ", Col01
? "Col02 = ", Col02
? "Col03 = ", Col03
? "Col04 = ", Col04

* GOTO 1 IN TableB    && **** THIS LINE ****

INSERT INTO TableB (Col01,Col02,Col03,Col04) VALUES (Col01,Col02,Col03,Col04)
INSERT INTO TableB (Col01,Col02,Col03,Col04) VALUES (Col01,Col02,Col03,Col04)
INSERT INTO TableB (Col01,Col02,Col03,Col04) VALUES (Col01,Col02,Col03,Col04)
INSERT INTO TableB (Col01,Col02,Col03,Col04) VALUES (Col01,Col02,Col03,Col04)

SELECT TableA
LIST

SELECT TableB
LIST

Notes
1. When the indicated line is commented out, you'll get blank records in TableB. If you uncomment, the records aren't blank.
2. Also notice the values that are populated in table when specified line is uncommented.