Nested IF Function

Hi Champs,

See below formula that i have updated in a cell.

Formula:

=(IF(L6<0,"Debit NLPX-VAA - Credit NLP MAIN",IF(L6>0,"Debit NLP MAIN - Credit NLPX-VAA",IF(L6=0,"No wire","Error"))))

If I updated any other character like an Alphabet or Symbol in L6, it still gives me one of the true values in the formula.
What i am expecting is that, if a user updates an Alphabet or Symbol in L6, the formula should populate "ERROR"

Can you please help.

Aaron