can a citizen of Ghana apply for a chinese work visa in Hong Kong?

Sir, I am a Ghanaian and my company has given me the Z type invitation document to exit mainland. Hong Kong was written on the document (that I should go there). However, I know that Ghanaians can not apply in Hong Kong, as many of my friends who went there were turned down. I even need to apply before I can enter Hong Kong. Do you think it's worth going to Hong Kong or I should rather go back to Ghana to apply for it. My current F type is even a zero entry which means I can't re enter the mainland if my applicaction is rejected. I need your expert opinion on this.
Thanks
Enock.