Pump Curve in WaterCad

Question

I got the pump curve from supplier and tried to insert it in WaterCad as a multiple point; but I got different shape and that our concern? why that happened and change the curve ? The Excel sheet gives us exact as the pump supplier..!! 
 The system Curve as per Supplier:

System Curve in Water Cad:

Points:

Pump 
 N 3153 LT 3~ 6p

Motor 
 N3153.181 21-18-6AA-W 9KW

Impeller 
 623 222mm

Flow [l/s] 
 Head [m]

0.50155 
 6.4638

7.0935 
 6.2591

13.685 
 6.0722

20.277 
 5.8583

26.869 
 5.6088

33.461 
 5.3338

40.053 
 5.05

46.645 
 4.7742

53.237 
 4.5194

59.829 
 4.2937

66.421 
 4.1003

73.013 
 3.9383

79.605 
 3.8038

86.197 
 3.6911

92.788 
 3.5934

99.38 
 3.5036

105.97 
 3.4148

112.56 
 3.3204

119.16 
 3.2139

125.75 
 3.0899

132.34 
 2.9436

138.93 
 2.7718

145.52 
 2.5732

152.12 
 2.3492

158.71 
 2.1046

165.3 
 1.8465

171.89 
 1.5841

178.48 
 1.3246

185.08 
 1.0672

191.67 
 0.79296

Regards, 
 Mohamad Azzam Pump Curve.xls

Jesse Dringoli · Accepted Answer

By default, WaterCAD uses a best-fit curve - notice the coefficients shown below the graph. If you do not want this, open the calculation options for your current scenario and select "true" for "use linear interpolation for multi-point pumps. 
 
If you do a search within the Hydraulics and Hydrology community, you'll see the below similar discussion: 
 
http://communities.bentley.com/products/hydraulics___hydrology/f/5925/t/22727