Ranking for lots of keywords, but one keyword phrase is being really stubborn - help

Hey everyone,

It's my first time here as I have a question I can't find the answer to on Google (believe it or not). I'm hoping someone will be able to help me.

I'm basically ranking for quite a few keywords (first or second) and I'm really happy how my SEO is going (I'm a newbie).

However, I have one keyword phrase I really want to rank for and I'm not even in the top 100 results. This keyword phrase is 'restaurant marketing'. I created a 'Skyscraper' article.

My articles are all in the same format and I seem to rank for most of the keywords I'm going for e.g. bar marketing, pub marketing, nightclub marketing etc. I'm 1st or 2nd for those. However, 'restaurant marketing' seems to be much more stubborn.

My question is... is there something wrong with my restaurant marketing article so it's being penalised? Or is it because it's a slightly harder keyword phrase to rank for? I'd be surprised if it's the latter because from page 4-5 the articles ranking get really ropey.

Any help on this would be really appreciated.

Thanks in advance.

Josh