How to add "numeric field" to a "date field" in Report?

Hi,

Good day!

We are currently working with Opportunity Record Type. In the report, we are trying to add "number of days" to a Date field.

Here is our formula:

TimestampAdd (interval, integer_expression, timestamp_expression)

TIMESTAMPADD(SQL_TSI_DAY, Cast("Sales Stage Metrics"."# of Days in Stage" as Integer), Cast("- Stage Start Date".Date as Date))

And we got this error:

View Display Error
	Odbc driver returned an error (SQLExecDirectW).   Error Details   Error Codes: OPR4ONWY:U9IM8TAC:OI2DL65P State: HY000. Code: 10058. [NQODBC] [SQL_STATE: HY000] [nQSError: 10058] A general error has occurred. [nQSError: 22025] Function TimestampAdd is called with an incompatible type. (HY000)