Writing a message on the Blockchain

Hi all, I'm trying to write a message on the Blockchain using Metamask and I keep getting the error message below. I've tried normal HEX and HEX leading with 0x. Just wondering if anyone knows what is going on and a possible fix. Thanks in advance!

Error
EthQuery – RPC Error – Error: Cannot convert string to buffer. toBuffer only supports 0x-prefixed hex strings and this string was given: