I am getting the following error message when analyzing my model

***ERROR***MATERIAL GROUP AND EXPLICIT CONSTANT SPECIFICATION CANNOT BE USED TOGETHER

EITHER USE MATERIAL GROUP NAME OR USE E/POI/DENSITY/ALPHA/G

TO ASSIGN CONSTANT TO MEMBERS/PLATES/SOLIDS.

Can you please suggest what could be causing this ?

An older way of assigning material to the structural members was by specifying the E, Density etc. under the CONSTANTS command and directly assigning to the members as shown next

So, for example, if you specify

UNIT INCH KIP
CONSTANTS
E 29000 ALL
DENSITY 0.283E-3 ALL
POISSON 0.3 ALL

This has however been replaced by a new way for material assignment where a material is defined first and then the material is assigned under the CONSTANTS as shown next

UNIT INCH KIP
DEFINE MATERIAL START
ISOTROPIC MATERIAL1
E 29000
POISSON 0.3
DENSITY 0.000283
END DEFINE MATERIAL

CONSTANTS
MATERIAL MATERIAL1 ALL

Both are acceptable approaches but one cannot have a mix of the two. If part of the assignment is done using the first method and part using the second method, the above error message is generated.