Validation rule in Opportunity Revenue Displays Error For All Cases

We are writing a validation rule to indicate that Quantity cannot be in decimal and Unit Price cannot be below Zero while adding a product. The script is written in Opportunity Revenue Object but the validation is shown for all positive scenarios too (Even if Price is above 0 and quantity is not decimal)

Steps to reproduce:

App Composer -> Opportunity Revenue Object -> Server scripts -> Validation rules -> Object Rules.

Groovy script written:

def regexQty = /^[0-9]*$/

if (!Quantity.toString().matches(regexQty))

{

 return false;

}

if (UnitPrice<0)

{ 

return false;

}

return true