Can't write an SMS for some of my contacts I'm using an LGP500 Android Phone (Android 2.2). In the default SMS application, when I select a discussion, I see the previous SMS (both sent and received), and there's a text area at the bottom of the screen to write a new message. 

For most of my contacts, this behavior is working correctly, but for a few of them (which I use quite often), the text area is not shown. Those contact have a mobile phone number, and I can send SMS using the long way (create a new sms, search the contact ...). 

Does anybody have an idea of the cause or the solution ? 

Edit I tried a few things to fix this : clearing the data, deleting any previous sms history, changing the phone number from the local (06xxxxxxxx) to international (+336xxxxxxxx) format (french phone numbers), changing the mobile phone number as default phone for the contact, in vain.
This is a problem i face with few contacts on my P500 too! Try merging contacts with their FB account or twitter account or just create a Buffer account and join them. It works after that. Not a great solution but been working that way now!