You missed widths marker for space char on the first line.
The drawgfxfont routine doesn't seem to haandle the "space" character, i.e. doesn't draw one. If I stick a space character in the font and include in the mask when loading the font it still doesn't work, try this fontTahoma 12pt bold
local tahoma12_font_image = loadimage("font_tahoma12.jpg")
tahoma12_font = loadgfxfont(tahoma12_font_image, "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!\"£$%^&*()_+=-#~'@;:?.>,<1234567890", 1)
This one doesn't have the space char but even if I add one it doesn't work - try drawing "Hello There!" - there is no space...