Hi, I have report where for particular field i am using an expression called. =Lookup(Fields!Transaction_Number,Fields!TransactionNumber,Fields!Credit.Value, "Overrides") But i am getting values like #Error. In the error list i am getting this error Warning 1 [rsLookupOfInvalidExpressionDataType] The Value expression for the textrun ‘Credit3.Paragraphs[0].TextRuns[0]’ uses a lookup function with an expression that returned a data type that is not valid for the lookup function. The data type must be an RDL Variant type. Transaction Number is of Varchar Type. Any ideas? why lookup is functioning like this.  Thanks

SSASStarter, Try modifying the type of TransactionNumber inside Lookup(), =Lookup( CStr(Fields!Transaction_Number) , CStr(Fields!TransactionNumber), CInt(Fields!Credit.Value) , "Overrides") Let me know if it helps. Regards, Manoj *Happy to help http://experiencingmsbi.blogspot.com/

Hi, Make sure your Transaction Number from Both datasets are of same datatype Varchar.Rakesh M J Dont forget to mark it as Answered if found useful MCTS,MCITP,MCSS http://myspeakonbi.blogspot.com/

Thanks, Manoj - Lookup function is not allowing explicit conversions. Rakesh - I have already made sure in my datasets to cast them in Varchar. But still it errors out. For the time being i have resolved my problem by using T-SQL. But i still want to know that why Lookup function is erroring out. Any more ideas? Thanks

Hi SSASStarter, Thanks for your question and other partners’ replies. Based on my research, source and destination expressions must evaluate to the same data type. The return type is the same as the data type of the evaluated result expression. So please check the field of Credit’s data type. For more detail information about lookup function, please refer to: Lookup Function (Report Builder 3.0 and SSRS) Hope it helps you. Thanks, Sharp Please remember to mark the replies as answers if they help you and unmark them if they provide no help.

Try this: =Lookup(Fields!Transaction_Number.Value,Fields!TransactionNumber.Value,Fields!Credit.Value, "Overrides") (added ".Value" for the first 2 fields) See sample at http://msdn.microsoft.com/en-us/library/ee210531.aspx: =Lookup(Fields!ProductID.Value, Fields!ID.Value, Fields!Name.Value, "Product")

Try to close project, then open it again, then write correct expression and run. It seems like lookup failure has a "memory effect" appearing.