In order to understand the error message, you have to know that the program uses two different unit sets with the same unit [kN/m3].
The first set (78) is used for most of the standard cases (LET #gamma 50[kN/m3]).
The second set (1091) is used for the density of a material in the command item “MAT GAM”.
The background for this case is described within the following chapter of the AQUA manual:
SSD / TEDDY > Help > User Manuals > All Manuals… > AQUA > 2.1 Materials
So if you preallocate the variable with the unit, the program actually allocates, in this special case, the “false” unit set.
Due to the program algorithm this behaviour will not be changed in the future. So as a workaround I would suggest to use the following code:
LET#gamma 50[-] $ [-] assignment of the variable without any unit
MAT NO 1 E #emod GAM #gamma[kN/m3]
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