When the beta-globin gene is inserted into the bacterial chromosome, during insertion, beta-globin forms a stop codon between the coding sequences of beta globin, resulting in a reduced amino peptide. Acid on translation
Furthermore beta-globins form a tertiary protein complex with alpha-globin, which in addition to the ham-subgroup forms functional hemoglobin.
Since we only put the beta-globin gene on the bacterium-chromosome that is not enough to make a functional protein, we found a non-functional protein