Nested If Statements

Having a problem creating a nested if statement. This works:

if((Imported_BPD > -1),Imported_BPD,((Feet * 12 + Inches + Quarter - Previous_Production_Inches) / ((Date_Time - Previous_Date_Time) / (1000 * 3600 * 24)) * Tank_Factor))

However, I am wanting to add another check to say if the formula is <0, then BPD = 0. Here is what I have tried but can't get it to work. Formula Field Both the argument should be same type for 'IF' task. Expecting 'IF' expression found 'BIGINT' expression

(

(Imported_BPD > -1),Imported_BPD,

if(

((Feet * 12 + Inches + Quarter - Previous_Production_Inches) / ((Date_Time - Previous_Date_Time) / (1000 * 3600 * 24)) * Tank_Factor) < Previous_Production_Inches, 0, ((Feet * 12 + Inches + Quarter - Previous_Production_Inches) / ((Date_Time - Previous_Date_Time) / (1000 * 3600 * 24)) * Tank_Factor)

)

I've also tried to use another formula field (inches per day) but can't seem to get that to work either.

Thanks,

Chris