STAAD not registering properties for tubular section

Good day.

I am trying to analyse an H frame structure and would like to replace my W8x18 beams with tubular sections that can compensate for the flanges' width. However when I try to simply replace the section and rerun my analysis an ERROR occurs and the program doesn't proceed with the calculations. Here is the input for the structure.

STAAD SPACE
START JOB INFORMATION
ENGINEER DATE 28-Jun-16
END JOB INFORMATION
INPUT WIDTH 79
UNIT MMS KN
JOINT COORDINATES
1 0 0 0; 2 0 2273 0; 3 0 2478 0; 4 0 5818 0; 5 0 8298 0; 6 0 10774 0;
7 0 11000 0; 8 0 11608 0; 9 6000 0 0; 10 6000 2273 0; 11 6000 2478 0;
12 6000 5818 0; 13 6000 8298 0; 14 6000 10774 0; 15 6000 11000 0;
16 6000 11608 0; 17 0 0 3000; 18 0 2273 3000; 19 0 2478 3000; 20 0 5818 3000;
21 0 8298 3000; 22 0 8650 3000; 23 6000 0 3000; 24 6000 2273 3000;
25 6000 2478 3000; 26 6000 5818 3000; 27 6000 8298 3000; 28 6000 8650 3000;
29 0 5818 1219; 30 0 5818 1781; 31 6000 5818 1219; 32 6000 5818 1781;
33 0 8298 1500; 34 6000 8298 1500;
MEMBER INCIDENCES
1 1 2; 2 2 3; 3 3 4; 4 4 5; 5 5 6; 6 6 7; 7 7 8; 8 9 10; 9 10 11; 10 11 12;
11 12 13; 12 13 14; 13 14 15; 14 15 16; 15 3 11; 16 4 12; 17 6 14; 18 17 18;
19 18 19; 20 19 20; 21 20 21; 22 21 22; 23 23 24; 24 24 25; 25 25 26; 26 26 27;
27 27 28; 28 19 25; 30 2 18; 31 4 29; 32 5 33; 33 10 24; 34 12 31; 35 13 34;
36 21 27; 37 29 30; 38 30 20; 39 31 32; 40 32 26; 41 29 31; 42 30 32; 43 33 21;
44 34 27; 45 33 34; 46 3 11; 47 19 25;
DEFINE MATERIAL START
ISOTROPIC STEEL
E 205
POISSON 0.3
DENSITY 7.68195e-008
ALPHA 1.2e-005
DAMP 0.03
TYPE STEEL
STRENGTH FY 0.2532 FU 0.4078 RY 1.5 RT 1.2
END DEFINE MATERIAL
MEMBER PROPERTY AMERICAN
7 14 17 30 31 33 34 37 TO 42 45 TABLE ST W6X15
15 28 46 47 TABLE ST W8X18
1 TO 6 8 TO 13 18 TO 27 32 35 43 44 TABLE ST W10X26
16 36 TABLE ST W12X40
CONSTANTS
MATERIAL STEEL ALL
SUPPORTS
1 9 17 23 FIXED
MEMBER OFFSET
15 START 0 0 -197.869
15 END 0 0 -197.869
46 START 0 0 197.869
46 END 0 0 197.869
47 START 0 0 197.869
47 END 0 0 197.869
28 START 0 0 -197.865
28 END 0 0 -197.865
DEFINE WIND LOAD
TYPE 1 WIND 1
<! STAAD PRO GENERATED DATA DO NOT MODIFY !!!
ASCE-7-2010:PARAMS 200.000 KMPH 4 2 1 0 0.000 FT 0.000 FT 0.000 FT 1 -
0 12.000 M 3.000 M 0.500 FT 0.600 2.000 0.010 -
0 0 0 0 1.040 1.000 1.000 0.850 0 -
0 0 0 0.885 1.600 -0.550
!> END GENERATED DATA BLOCK
INT 1.93496e-006 1.93496e-006 1.98353e-006 2.02801e-006 2.06911e-006 -
2.10735e-006 2.14316e-006 2.17685e-006 2.2087e-006 2.23891e-006 2.26767e-006 -
2.29512e-006 2.32139e-006 2.34659e-006 2.37082e-006 2.37082e-006 HEIG 0 4572 -
5143.38 5714.77 6286.15 6857.54 7428.92 8000.31 8571.69 9143.08 -
9714.46 10285.8 10857.2 11428.6 12000 12000
EXP 1 JOINT 1 TO 34
DEFINE UBC LOAD
ZONE 0.04 I 1 RWX 4.5 RWZ 4.5 STYP 3 NA 0.5 NV 0.5
SELFWEIGHT 1
MEMBER WEIGHT
28 47 CON 2.85 1198
28 47 CON 2.85 2698
28 47 CON 2.85 4198
15 46 CON 2.5 1500
15 46 CON 2.5 3000
15 46 CON 2.5 4500
41 42 CON 3.39 500
41 42 CON 3.39 3000
41 42 CON 3.39 5500
45 CON 0.5 3000
LOAD 1 LOADTYPE Seismic TITLE EQX
UBC LOAD X 1
PERFORM ANALYSIS
CHANGE
LOAD 2 LOADTYPE Seismic TITLE EQZ
PERFORM ANALYSIS
CHANGE
LOAD 3 LOADTYPE Dead TITLE DEAD LOAD
SELFWEIGHT Y -1
MEMBER LOAD
28 47 CON GY -2.85 1198
28 47 CON GY -2.85 2698
28 47 CON GY -2.85 4198
15 46 CON GY -2.5 1500
15 46 CON GY -2.5 3000
15 46 CON GY -2.5 4500
41 42 CON GY -3.39 500
41 42 CON GY -3.39 3000
41 42 CON GY -3.39 5500
45 CON GY -0.5 3000
16 CON GZ -0.5 3000
36 CON GZ 0.5 3000
CALCULATE RAYLEIGH FREQUENCY
LOAD 4 LOADTYPE Live TITLE LIVE LOAD
LOAD 5 LOADTYPE Wind TITLE WIND LOAD
LOAD 6 LOADTYPE None TITLE MODAL CALCULATION
SELFWEIGHT X 1
SELFWEIGHT Y 1
SELFWEIGHT Z 1
LOAD COMB 7 COMBINATION LOAD CASE 7
3 1.4
LOAD COMB 8 COMBINATION LOAD CASE 8
3 1.2 4 1.6
LOAD COMB 9 COMBINATION LOAD CASE 9
3 1.2 5 0.8
LOAD COMB 10 COMBINATION LOAD CASE 10
1 1.0 3 1.2 4 0.5
LOAD COMB 11 COMBINATION LOAD CASE 11
2 1.0 3 1.2 4 0.5
LOAD COMB 12 COMBINATION LOAD CASE 12
1 1.0 3 0.9
LOAD COMB 13 COMBINATION LOAD CASE 13
2 1.0 3 0.9
PERFORM ANALYSIS PRINT ALL
PARAMETER 1
CODE LRFD
DFF 360 ALL
CHECK CODE ALL
PARAMETER 2
CODE LRFD
SELECT MEMB 1 TO 28 30 TO 45
GROUP MEMB 7 14 17 30 31 33 34 37 TO 42 45
GROUP MEMB 15 28 46 47
GROUP MEMB 1 TO 6 8 TO 13 18 TO 27 32 35 43 44
GROUP MEMB 16 36
PERFORM ANALYSIS
STEEL MEMBER TAKE OFF ALL
CHECK CODE ALL
FINISH

I thank you all in advance for any and all assistance or guidance you are willing and able to provide.