sql query results not working on last day of the month

I have a sql query which is producing accurate results every day but the last day of the month. The last day of the month the result set has zeros rather than the real totals for the data set. the column period balance returns zeros rather than the totals as it does the rest of the days of the month. I need for this to return a result set with the accurate totals for that day as the other days in the month. I do have a way to validate that number outside of SQL. the provider will have remote shared or monitored access to the sql report. sole or singe access will not be part of this job, team viewer or another tool can be used, but the sign on will be a shared screen not by individual.