Simple Criteria syntax mismatch - please help!

[whatwouldmattdo]

Hi guys, just had a really quick question.. I've made the following query that takes readings from stages of a Lauter Tun (industrial beer brewing vessel).. I keep getting "Data type mismatch in criteria expression" and after some tweaking i can get the error "Invalid use of null". I swear I've tried everything and most internet assistance on the matter deals with date formatting etc - really shouldn't be so hard!

Here's the query I'm trying to write

SELECT [qBH 011 - BH_PROCESS].[Start Date/Time], [qBH 011 - BH_PROCESS].[End Date/Time], [qBH 011 - BH_PROCESS].[Recipe Type], [qBH 011 - BH_PROCESS].Recipe, [qBH 011 - BH_PROCESS].[Week #], [qBH 011 - BH_PROCESS].[Brew #], [qBH 011 - BH_PROCESS].[D09 Name], [qBH 011 - BH_PROCESS].[D04 Actual], [qBH 011 - BH_PROCESS].[Step Name], Val([D09 Actual]) AS Expr1
FROM [qBH 011 - BH_PROCESS]
WHERE ((([qBH 011 - BH_PROCESS].[D09 Name])="LT1_DENSITY") AND ((Val([D09 Actual]))>0));

When it's like this (missing essential criteria expression) it works:

SELECT [qBH 011 - BH_PROCESS].[Start Date/Time], [qBH 011 - BH_PROCESS].[End Date/Time], [qBH 011 - BH_PROCESS].[Recipe Type], [qBH 011 - BH_PROCESS].Recipe, [qBH 011 - BH_PROCESS].[Week #], [qBH 011 - BH_PROCESS].[Brew #], [qBH 011 - BH_PROCESS].[D09 Name], [qBH 011 - BH_PROCESS].[D04 Actual], [qBH 011 - BH_PROCESS].[Step Name], Val([D09 Actual]) AS Expr1
FROM [qBH 011 - BH_PROCESS]
WHERE ((([qBH 011 - BH_PROCESS].[D09 Name])="LT1_DENSITY"));

but doesn't filter out the =0 values.

[June7]

Why do you need to use Val function? What is data in [D09 Actual]?

Val function can't handle null so try:
Val(Nz([D09 Actual],0))

[orange]

Further to June's remarks, why do you have spaces and slashes in your Names? This will come back to bite you again and again.

[June7]

And more - spaces, special characters, punctuation in names can all be source of aggravation. If used, must always remember to enclose names in []. Only exception is the underscore. Also, same for reserved words used as full names.

[whatwouldmattdo]

Thanks June - it worked perfectly! I will have to pay more attention to simple variable types and their capabilities in future.

Orange; thanks for the tip - naming conventions are something I'm starting to get the hang of.. Definitely makes life easier. I'll fix them up today actually - Cheers guys!