Range of LOCATE arguments are 0-49 (for X) and 0-29 (for Y) on top screen. LOCATE 0,0 is top left corner of top screen, and LOCATE 49,29 is bottom right corner. And I guess Z coordinate of LOCATE you've set is too low.
Try replacing line 141 and 142 of your attached program with the following.
LOCATE 13,15,-8
PRINT"YOU COME ACROSS A RIVER"
1そうだね 未プレイ