Expression Issue used for CPV type chart

[spikenaylor1]

Any help for the below issue would be greatly appreciated

I am charting strength per batch

each Batch could have been made a with different strains. We have 4 categories of strain but could have 2 strains in one category

my chart shows strength for each batch sorted by autonumber(Strain)

I am wanting to show historical mean, SD, UCL and LCL Values on the chart. 

I have a separate imported table with the historical data, Year, Category, Mean, SD values

I can manage to display the Mean and SD etc for the Categogories.

This is my Expression to display the Mean Historical Value

however, we may need to display different Mean,SD for a any new strains coming in until we can incorporate the data into the correct Category.

I can achieve this with one new strain, but not with 2 new strains. (Example, just loading Strain 1 or Strain 2 gives the correct Mean displayed on the chart, loading both together causes the chart to ignore both sets of data for Strain 1 and Strain 2)

=
IF(BatchStrain <> CPVBatchStrain,

			If(Category = 'TypeA',
			Only({<CPVCategory={'TypeA'}>}StrengthMean)
			,
			If(Category = 'TypeB',
			only({<CPVCategory={'TypeB'}>}StrengthMean)
			,
			If(Category = 'TypeC',
			only({<CPVCategory={'TypeC'}>}StrengthMean)
			,
			only({<CPVCategory={'TypeD'}>}StrengthMean)
			)
			)
			)
,
only({<CPVBatchStrain=P(BatchStrain)>}StrengthMean)

)

field starting with CPV are from the loaded table for Historical CPV Data

example below

Year	CPVCategory	CPVBatchStrain	Mean	SD
2019	TypeA	-	8.12	0.14
2019	TypeB	-	8.16	0.15
2019	TypeC	-	8.45	0.3
2019	TypeD	-	8.41	0.31
2019	-	Strain1	7.5	0.1
2019	-	Strain2	8.05	0.07