User exit : RSRT - OK, error in BEx

Hello,

In BEx I have a variable based on 0CalQuarter of type user exit. When I try to execute my report with this variable from BEx Designer in web I got an error "Value 1 for variable MYVAR is wrong". Debugging in RSRT shows no errors, variable is filled properly and the report is generated. Where should I look for a cause of this problem? Any ideas?

Thanks in advance.

Best regards,

Eugene