It looks to me like you're waiting for the letter "K" to come in from the word "blink". Picbasic will wait until it sees the letter "K", and then the next character is placed into your variable. What is the next character after the "K"? Nothing. Hence you will return the value zero. Try it without the wait, or try something like
hserin 100,,[str Variable\5\$6b]
This will take in a string of five characters, or fewer if it sees the hex value 6b, which should be the ascii value for a lower case letter "k" if I read it right. (The print is small on my ascii table, and I forgot my glasses!)

Hope this helps.

Jerry.