We are receiving an error when we are trying to add a line item manually using commerce manager

Hi,

We are facing the below exception when we are trying to add a new line item to the purchase order.

[FormatException: Input string was not in a correct format.]
   System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal) +14777731
   System.Number.ParseInt32(String s, NumberStyles style, NumberFormatInfo info) +172
   Mediachase.Commerce.Manager.Apps.Order.EntryTypes.CatalogEntry.InitializeForm(Entry entry) +728
   Mediachase.Commerce.Manager.Apps.Order.EntryTypes.CatalogEntry.LoadContext(IDictionary context) +264
   Mediachase.Commerce.Manager.Apps.Order.Modules.CatalogEntrySearchDialog.ConfigureButton_Click(Object sender, EventArgs e) +1082
   System.Web.UI.WebControls.Button.OnClick(EventArgs e) +11798065
   System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +150
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1669

We have added two custom metal fields of property type longstring in the purchase order. We tried to find the reference for Mediachase.Commerce.Manager.Apps.Order.EntryTypes.CatalogEntry. please suggest what could be the issue?