time interval issues

[guyd123]

hi all,
i have several issues concerning time intervals:

1. whenever i want to display a time-interval on a chart of any sort, if the interval is above 35~ days, i get an RSVARIANT error. Is this a known issue with 8.4? Is there a solution, besides casting the data to an int and displaying it that way?

2. also, when displaying time intervals on a chart, i want the axis and the series to be conditionally formatted to show only the relevant time units (anything under an hour will show as minutes, above that and under 48 hours will show as hours and more than that as days). when i set up a conditional style according to the interval, i get an error saying that a comparison cannot be made between a double and an interval2 datatype. cognos casts the data from the conditional style like this : string2DTinterval("0 02:53:00.221"), but I'm not allowed to use this function. my time interval is created by subtracting date-times. is there a way to cast it so the condition will work?
Is there some other way to achieve what i want? by default cognos show time intervals in milliseconds, and if you choose which time-units to show globally, then they are rendered even if they are null : 0 days 0 hours 0 minutes 5 seconds. Can i somehow avoid the null units?

thanks guys