Should Be Equal As Strings

Robot Framework
1

Hello,
im trying to compare two same strings in RIDE. The two strings are same:
{a} | kInvalid {b} | kInvalid

Should Be Equal As Strings {a} {b}

i get this on the log:

FAIL: kInvalid != kInvalid

can anyone help plz ?

2

The correct syntax is:
Should Be Equal As Strings ${a} ${b}

(I see the $ were removed on this message)