getting #VALUE ERROR in Excel IF function

I get #VALUE ERROR with a formula containing multiple IF conditions in cell H12:

=IF(AND((C6/C4)<=1,C10=0),1+0.4*C6/C4, IF(AND((C6/C4)<=1,C10>0),H13-((1-H13)/(C12*TAN(C10))))), IF(AND((C6/C4)>1,C10=0),1+0.4*ATAN(C6/C4), IF(AND((C6/C4)>1,C10>0),H13-((1-H13)/(C12*TAN(C10)))))

Based on this:

I'm using Excel 2013.