This is the code I been working on, but I need help for some reason the last two lines are not correct (Atmel Studio Assembly)

E2.7 Write a sequence of instructions to add the three numbers stored in data memory loca- tions at 0x2000, 0x2001, and 0x2002 and store the sum at data memory location at 0x2010. ;solution: To read three numbers from memory, then add them and store result ldi XL,exee ; let X point to ex2000 ldXH,0x20 ; " ld YL'exal ; let Y point to 8x2001 ld YH, 8x29 ;" ldi ZL, exe2 ; let Z point to ex2002 ldi ZH, 0x29 ;" ld re,x ;load the contents of ex2ee0 to re ld r1,Y load the contents of ex2001 to rl ld r2,Z ;load the contents of 0x2002 to r2 add r2,r1,re; add the two numbers std X+0x20,r1; store the sum at 0x2010 List e Solution 2 ErrorsWarnings 0 Messages Build IntelliSense Description Invalid register Wrong number of operands