There's a problem when I run my design. Ngene showed the massage:

A valid initial random design could not be generated after approximately 10 seconds. In this time, of the 189399 attempts made, there were 0 row repetitions, 11920 alternative repetitions, and 177479 cases of dominance. There are a number of possible causes for this, including the specification of too many constraints, not having enough attributes or attribute levels for the number of rows required, and the use of too many scenario attributes. A design may yet be found, and the search will continue for 10 minutes. Alternatively, you can stop the run and alter the syntax.

Below is my codes:

- Code: Select all
`Design;`

;alts = alt1*,alt2*,nobuy

;rows = 32

;eff = (mnl,d)

;block = 4

;model:

U(alt1) = b1[-0.81] * price[4.45, 8.45, 12.45, 16.45] +

b2.dummy[0.94] * Or[0,1] +

b3.dummy[0.55] * Ft[0,1] +

b4.dummy[0.22] * Ct[0,1]

/

U(alt2) = b1 * price +

b2 * Or +

b3 * Ft +

b4 * Ct

/

U(nobuy) = b0[-8.68]

$

Are there somethings wrong in my codes? How should I solve this problem?

Thanks for your helps.