"Check for incorrect argument data type or missing argument in call to function 'symsum'".Why this error ?

While write this summation equation "∑_(j=1)^4=〖(x_ij^k+V^k)〗"using symsum shown this error 'Check for incorrect argument data type or missing argument in call to function 'symsum''.

[Steven Lord]

Please show us the code you've written that includes your symsum call as well as the code that sets up any variables you use in that symsum call.