$=$IF$($B$11<=$$M$$3,0,-$PPMT$($$E$$6,$B$11,$$G$$4,$$E$$2))$

b$11=$ loan month, with it being loan month #$1$

$m$$3=$ I$/$O Period ending month, with the value being on month $12$

$E$$6=$ monthly interest rate, with it being $\mathrm{.}5\%$

$G$$4=$ term of amortization with it being, $288$ months

$E$$2=$ Principal amount $$1,000,0000$

What$$s wrong with the Principal Portion formula in cell G$11$ of the Excel?

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$1.$ It does not need a negative sign in front of the PPMT function

$2.$ It should use $360$ months of amortization

$3.$ It equates the loan month # with the amortization month #

$4.$ There is nothing wrong with it