Hi, I have two tables named Ingreso and Trabajo. They look like this:

Ingreso
folioviv foliohog numren clave ingreso
1001 1 01 P022 5005
1001 1 01 P040 4500
Trabajo
folioviv foliohog numren id_trabajo sinco
1001 1 01 1 4111
1001 1 01 2 3101
How should I merge trabajo to ingreso?

I've tried
Code:
merge 1:m folioviv foliohog numren id_trabajo using Trabajo, keepusing(sinco)
merge 1:m folioviv foliohog numren using trabajos, keepusing(sinco)
merge m:1 folioviv foliohog numren id_trabajo using Trabajo, keepusing(sinco)
but I get the error: variable id_trabajo not found
or
variables folioviv foliohog numren do not uniquely identify observations in the master data

I know i shouldn't use m:m but I'm stuck