data typing; script error

I have an app with a subform. The whole form looks something like:

Client - a lookup

Project - a lookup

Employee Hrs Rate Bill_Amt (a line of the subform)

After entering Employee, I want to lookup the associated Rate and insert in the Rate field above.

I am trying some scripting :

theRate = Employees[ID == row.Employee].Rate;

alert(isNumber(theRate)); //used for debugging returns true.

row.Rate =theRate;

When I go to save the script, I receive :

Error at line number : 3

Expecting BIGINT expression found DECIMAL expression

Do I need to do some data typing on theRate or row.Rate or ???

Any help appreciated.

Thanks!