Bootloader. Writing strings to the screen

Question

I've written some simple bootloader that works good in QEMU and I decided to try it on real machine. I copied image file to flash drive and tried to load from it. But for some reason I've been getting just black screen with cursor somewhere near the top left corner and it made me think that it might be some problem with displaying strings on the screen. To check that idea I wrote simplistic bootloader that shows a message "Loading Image " and checks whether IO extensions (int 13h ah=42) are supported.If it's supported shows the message "Extensions are here". So in qemu it works and I'm getting these two messages as expected. But on my computer instead of two lines I'm getting one line like this "LoaExtensions are here". To print message I use int 10h ah=0Eh I tried to set different video modes using ah=0 function of the int 10h but I've always got the same result. Could you please help me to understand what could be wrong? This is the code:

bits    16                      ; we are in 16 bit real mode
org     0                       ; we will set regisers later
start:  jmp Main                    ; jump to start of bootloader


msgLoading              db "Loading Image ", 0x0D, 0x0A, 0x00
msgSectorReadingError   db "ERROR: Can't read sectors from disk",0x0D,0x0A, 0x00
msgExtNotSupported      db "ERROR: BIOS doesn't support LBA",0x0D,0x0A, 0x00
msgErrWhileLoadingImage db "ERROR: Couldn't read seconday image",0x0D,0x0A, 0x00
msgExtSupported         db "Extensions are here",0x0D,0x0A, 0x00
imgName                 db "STAGE2  SYS"
;************************************************;


;************************************************;
;   Prints a string
;   DS=>SI: 0 terminated string
;************************************************;
Print:
            lodsb               ; load next byte from string from SI to AL
            or  al, al          ; Does AL=0?
            jz  PrintDone       ; Yep, null terminator found-bail out
            mov ah, 0xE         ; Nope-Print the character
            int 0x10
            jmp Print           ; Repeat until null terminator found
PrintDone:
            ret             ; we are done, so return

;************************************************;
;   Set Video mode
;
;************************************************;
SetVideoMode:
            mov ax,0x0002
            int 0x10
            ret


;***********************************************;
;   Checks whether BIOS supports extensions
;************************************************;
CheckExtenstions:

        xor ax,ax
        mov ah,0x41
        xor dx,dx
        mov dl,BYTE[driveNumber]
        mov bx,0x55AA
        int 0x13
        cmp bx,0xAA55
        jnz .error
        test cl,0x1
        jz .error
        jmp .exit
.error:
        mov si,msgExtNotSupported
        call Print
        cli
        hlt
.exit:
        mov si,msgExtSupported
        call Print
        cli 
        hlt
        ret




Main:

        ;----------------------------------------------------
        ; code located at 0000:7C00, adjust segment registers
        ;----------------------------------------------------

        cli                             ; disable interrupts
        mov     ax, 0x07C0              ; setup registers to point to our segment
        mov     ds, ax
        mov     es, ax
        mov     fs, ax
        mov     gs, ax

        ;----------------------------------------------------
        ; create stack
        ;----------------------------------------------------

        mov     ax, 0x0000              ; set the stack
        mov     ss, ax
        mov     sp, 0xFFFE
        mov     BYTE[driveNumber],dl
        sti                             ; restore interrupts
        call SetVideoMode
        mov     si, msgLoading          ; Show Loading Message
        call    Print

        call CheckExtenstions

        cli
        hlt

TIMES 510-($-$$) DB 0
DW 0xAA55