how to be friendly with other childrens parents on school run!

[chumble]

DS is at school and has been for two years. I am on talking/chatting terms with all of the mums except a couple who for some reason or other don't want to talk/chat or exchange the time of day at drop off or pick up.

Ds is starting to play with the children of these mums and I would like to be on talking terms with their parents at least! How can I achieve this?

I know it may sound strange but I have tried smiling and general chat during the first year and this did not seem to work so now I have given up. However I realise that our children will share the same class for several years to come it would be nice to at least acknowledge each other! Or should I just accept it how it is and let things develop 'naturally'! I just find it all very uncomfortable.....

Thanks in advance

It's really interesting how widespread this problem is. I had a group of mums I used to get on well with and then one of them just started blanking me and this carried on for a year and a half. I still wanted to be friends with the other mums in the group but it was difficult as they still thought the one that blanked me was the bees knees. If they had to choose between standing with me or her it would always be her. It has really affected my mood as it reminds me of being at school and not being in the 'in' crowd due to being overweight and having an autistic sibling who everyone kept asking me about - "what's wrong with your brother?" Sometimes it really gets me down as I've never found out the reason that this mum blanked me even though I've spoken to her about it. I think the other mums in the group just think I'm really sensitive when in actual fact I just don't want to be around that woman and if that means not hanging out with the whole group so be it.
Why are some women so bitchy? I've thought about the situation so much over the last few years and it's really getting on my nerves that I can't get it out of my mind. I feel rejected all over again - after feeling like that at school.