In VFP 6, you can use Insert-SQL with this syntax only

insert into table1 from memvar
or
insert into table1 (field1,field2,field3) values (val1,val2,val3)
or
insert into table1 (field1,field2,field3) values (table2.field1,table3.field2,table1.field3)


This syntax which you are trying to use is not supported in VFP 6.