MIPS UART Palindrome Checker PLP5.2

I have written the following code for a UART Palindrome Checker but it is not working properly. can someone please help me figure out where I am going wrong? The program is using MIPS and PLP 5.2 platform to read strings and print a "yes" or "no" if they are or are not palindrome. Right now when I load the program it is printing a "no" before i put a string in and no matter if the string is the same forwards and backwards it is printing a "no". Also the program uses a "." to separate strings to be evaluated.