Having trouble sending texts to a specific number

[Anonymous]

Hey guys,

Since Tuesday I have been unable to send SMS to a specific person. but I am still able to perfectly send texts to all other contacts, I don't think it's an issue with number blocking, as I can make calls to her, and she can to me. Also, I can recieve texts from her, the noly problem is when I send texts to her. I'm using a Samsung Galaxy Ace. Any thoughts? 

P.S. : I have tried inserting my SIM into another Galaxy Ace, and that didn't work, but a friends SIM in my phone did work. 

[jonsie]

To be honest it sounds as though you have blocked the number on your phone especially if that number is stored on the sim as well.

Check in your message settings for blocked numbers and reset to default settings. Failing that you might try deleting her from your contacts and then re-adding. Reboot your phone then try sending her a text.

[Anonymous]

Already tried all those steps, and the number definitely not blocked or stored on the SIM.

[Anonymous]

I would hazard a guess that what Jonsie says is correct except it is the recipent that has blocked you. 
Do they have a samsung handset as it is really easy to do it by accident?