Hello,
Please refer to the attached sample working correctly at my end with the latest C1Silverlight Build : 5.0.20133.378 available at :
prerelease.componentone.com/hotfixes/silverlight/C1Silverlight_5_5.0.20133.378_RC1.msi
If the issue still persists, then you are requested to share a stripped down sample of your code replicating the issue or make the necessary changes to this sample, so that I could debug the issue at my end and provide you with appropriate assistance.
Regards,
Reema