PL/SQL: numeric or value error: character string buffer too small %ROWTYPE

I don't know if I am missing something but what I am doing is:

I have a function that returns a ROWTYPE

  FUNCTION myFunc(pChar CHAR) RETURN myTable%ROWTYPE AS
    myTable_rec myTable%ROWTYPE;
  BEGIN
    SELECT col1, col2, col3
    INTO myTable_rec.col1 
      , myTable_rec.col2
      , myTable_rec.col3
    FROM myTable
    WHERE col4 = pChar;

    RETURN(myTable_rec);
  END B001_03;

then in my procedure (which calls the function above), I declared:

myTable_rec myTable%ROWTYPE;

but when I call in the procedure:

...
myTable_rec := myFunc(someChar);
...

I get

ORA-06502: PL/SQL: numeric or value error: character string buffer too small

Aren't the fields supposed to be FROM the same table and OF THE SAME datatype (as of my little understanding)?

EDIT: I tried to SELECT * and every works. I am definitely missing something here. I just don't know that it is.