Dynamic schemes with formulas

Hi everyone,
is there a correct way to use formulas in dynamic schemes measures?
For instance I’ve got the following piece a static scheme that works fine:

measures: {
count: {
type: count,
title: ‘Some counting measure’
},
payment: {
sql:‘c19::FLOAT’ ,
type: sum,
title: ‘Clients who paid’
},
conversion_payment: {
sql:${payment}/${count} ::DECIMAL * 100.0 ,
type: number,
format: percent,
title: ‘Conversion into payment,%’
},

My endpoint returning dynamic schemes produces the following:

“measures”: {
“count”: {“type”: “count”, “title”: “Some counting measure”},
“payment”: {“sql”: “c19::INTEGER”, “type”: “sum”, “shown”: true, “title”: “Clients who paid”},
“conversion_payment”: {“sql”: “${payment}/${count} ::DECIMAL * 100.0”, “type”: “number”, “title”: “conversion into payment”, “format”: “percent”}

And I get “Error: syntax error at or near “$”” with dynamic schemes when I choose “conversion_payment” measure. Definitely my syntax is wrong.
Can anyone advice on that?