how do i upload a photo from iPhoto to twitter?

hi peeps,

wonder if anyone can help...i have been trying to upload a pic from iphoto to twitter and it wont let me, the twitter icon is not able to be selected.

I have tried deleting my twitter info from preferences and re inputting it but that didnt work. the onlu option that is allowed currently is mail.

I was able to upload the pics to facebook last night but now the facebook button is not able to be selected too.

please help

many thanks

ian