Conditional formatting to color only cells in one row

hey guys

i am completely new to the forum and i am lost with this problem that i have in excel 2010.
see the attached "Cond_form_date.xlsx" file.

what do i want to achieve?

i want any cell in the column A to turn red whenever i type an x into any cell right of it (so, from column B to ...).
because every column right of the column A represents one day there will be quite some columns (around 1500). that means i reach columns with triple letter length, such as BBB, etc.

my format value is e.g.:
=IF(AND(K1 = "x"; K$1 <> TODAY()); 1; 0)

the AND function is not giving me any headaches. my problem is, that if i choose K1 = "x" and today's date is not today, the column A cells turn red!
SUPER! BUT!

if i write an x to let's say a cell of the column P, it will not color the cell in the column A but the cell in the column F instead, which is exactly the distance from A to K. that means, the cell coloring happens "K cells later".

my first idea was to just get the actual column letter(s) and then it would work out fine. like this:

'current cell letter'1 = "x"

leads to

INDIRECT(LEFT(ADDRESS(ROW(); COLUMN(); 4); MIN(FIND({0,1,2,3,4,5,6,7,8,9}; ADDRESS(ROW(); COLUMN(); 4)&"0123456789"))-1)&1) = "x"

it does not work because apparently one cannot use such functions for conditional formatting.
4 hours wasted, great. but i did not want to give up. tried it with a dirty trick.
with a 2nd worksheet 'rows as row' i tried to not use any MIN etc. functions. that led to

INDIRECT(INDIRECT("'rows as row'"&"!A"&COLUMN())&5) = "x"

now excel did not complain but it still does not work!!!


how come? i do not understand it anymore.
does anyone of you guys know a solution? i would appreciate it a lot!

thanks in advance
nivoe

PS: i do not wish for any VBA solution. that is neither slick nor cool. especially when sharing the document with lots of people with different rights, etc.