Help with business map - validation

[rslemer]

I wish in payments if a specific value in my picklist another filed is a range min 01 max 10

In fact, if type of payments is a Credit Card, I wish a number of payments (another custom field ) only has a value between 01 to 10

Example

my custom field

Called "type of payments"

...
...
Credit Card
...
...

If value select in this list is Credit Card another custom field

Nr of Payments is mandatory, and a valid value is 01 to 10

..
I know is possible with a business map, but I not able to created a correct syntax