Components ignoring conditions when leave without pay is involved

I have a component colled Income tax (IT) and it depends on basic salary (B) which is dependant on leave without pay. only people earning morethan $350 are suppose to pay IT. So I set a condition which says for B < 350, IT = 0 and for B > 350.01, IT = ((B - NSSA) * .2) - 70. For conditions were the B salary is not affected by leave without pay the formulaes works perfectly, but when the leave without pay reduces the basic salary to lessthan $350 it uses the formulae IT = ((B - NSSA) * .2) - 70 instead of inserting 0

What can be the issue ?