Missing legends on graphs plots from Sql

We have set up a graph plot which generates a colored legend for each soil unit on our graphs. The legend works when plotting directly from a .gpj and when plotting from a single project from our sql server. When including data from 2 projects on one graph, the plot is fine but the legend is missing. Have other users experienced the same and what did you do? Examples can be provided by mail.

The legend is generated from the following code:

<<Let(Layer Code = _
  <<RecordItem(<<GEOLOGY_UNIT_1.ItemKey>>,<<#>>)>>_
)>>_
<<ListBuildSepTrim(_
  ":  ",_
  <<let(c=<<Lookup(<<GEOLOGY_UNIT_1.Colour_NO>>,<<Get(Layer Code)>>)>>)>><<clr!<<get(c)>>>><<Get(Layer Code)>><<Clr!-1>>
)>>

- Martin