Paste Update Negative Numbers to UD field causes error

Hello All,
I created a field GLBudgetDtl.Forecast_c as an integer with the format ->,>>>,>>>,>>9. I can manually enter a negative number into the field in my dashboard with no problems. If I try to do a paste/update I get the error “The value -1 for column: GLBudgetlDtl_Forecast_c is not valid. The import has been canceled.” Has anyone ran into this problem? I can’t seem to find the cause.