Smart Keyboard Forum

I was wondering if anyone out there has had the same problem I have had with Smart Keyboard. I'm not sure if this is a problem with my phone or the program itself. I use Smart Keyboard for texting in Japanese. Every now and again when I receive a text message from one of my Japanese friends, the characters will come up as question marks. This does not happen all of the time, but lately it has been happening very frequently. They can read my texts I send in Japanese okay. Any suggestions or fixes would be greatly appreciated. Thanks.