work – Visa Rejection for Germany

I applied for a work visa to Germany having received my contract from the Employer as a parcel delivery driver. I provided all the necessary documentation requested by the Embassy in my country but all in vain.

The reasons are as follows;
You intend to enter Germany for gainful employment as Parcel delivery.
A necessary offense according to the Employment Ordinance or the Residence Act is taking into account your nationality and the desired activity unavailable.
A visa according to 24a BeschV as a professional driver is out of the question here as you do not have a corresponding Driver attestation within the meaning of Article 5 (1) of the Regulation
EG) No. 1072/2009.

1-How can I appeal and what supporting documents does the Embassy require to for me to prove to them.
2- Can some explain to me if it’s an offense for me to acquire gainful employment as a parcel delivery driver